New Presentation - Coatings and Refractory

Coatings, Insulation, Fireproofing, and Monolithic Refractories

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Coatings, Insulation, Fireproofing, and Monolithic Refractory 

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This seminar will introduce the attendee to the basic principles of coatings, Insulation, Fireproofing, and refractory linings. The attendee will learn the function of each of the systems discussed and will be aware of the major benefits and drawbacks of each.

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Coatings

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Coatings

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In this session the basic concepts applicable to coatings will be introduced, including where coatings are used, types, surface preparation, application, and inspection/repair.

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The attendee will understand the components of a coating system, and the role of each. They will also be able to recognize common coating damage mechanisms, and the conditions that cause them.

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Coatings

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Topics — References — Role of coatings — When Coatings are Used — Types of Coatings — System Selection Considerations — System Specification — Surface Preparation — Application — Inspection — Damage Mechanisms RE/Coatings-5

Coatings - References 

The Steel Structures Painting Council (SSPC) is the primary source for information and requirements pertaining to painting, particularly surface preparation, application, and inspection. — Appendix A contains a listing of the most used

standards. — The SSPC website (www.sspc.org) is a good source of

information. One feature is a paper posted each month for free download. A sample from a recent month, “Coating Systems for Elevated Temperature Surfaces” is included in Appendix C.

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Coatings - References

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Process Industry Practices (PIP) has an extensive listing of coating practices. A listing of the most applicable is included in Appendix A. Also see their website at www.pip.org Vendor information – many requirements are system and even product specific. These are available for the vendors, often from their website. Appendix B contains a short list of terms and their definition. NACE and ASTM also have several applicable documents – See Appendix A.

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Role of Coatings 

Role or purpose of coatings — Coatings are applied to surfaces (typically metallic)

to protect the substrate from a corrosive environment. This is done by either:

— Separating the substrate from the environment — Creation of a galvanic cell where the coating is

the anode and suffers corrosion loss instead of the substrate — Some coatings are intended to provide an indication

of elevated temperature or, occasionally, the presence of a leak or other undesirable material.

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When Coatings are Used 

Coatings are used in accordance with industry standards and/or refinery policy. — If no other information is available, consider coating carbon and low

alloy steel — uninsulated surfaces — insulated surfaces operating above -50ºF (-45ºC) and below 300ºF (150ºC) — under fireproofing and insulation Water and corrodents can be trapped   Not accessible for inspection for cleaning — under refractory if Surface is below the atmosphere dew point  High temperature corrodents are present at the metal  surface Water may condense on the surface  — for shipment if not protected from corrodents, water, salt, etc — Consider coating insulated stainless steel surfaces operating above 50ºF (-45ºC) and below 300ºF (300ºC) RE/Coatings-9

Types of Coatings 

For the purposes of this seminar, coatings are defined as thin protective layers placed on the exterior surface of the substrate. — They are placed in liquid form and dry, or set as the result of a catalytic reaction. — Thin means their thickness is measured in mils

(thousandths of an inch). — Most are, essentially, paint-like. Specialty coatings or

linings (e.g., rubber, PTFE, coal tar on buried vessels, etc) are not included. 

Nearly all must provide a solid, continuous barrier, isolating the substrate from the corrodent, in order to be effective. Corrosion will occur at any opening, damaging the substrate and progressively damaging the lining. RE/Coatings-10

Types of Coatings 

Most coatings are made of two or three components: — Binder – this is the material (generally resin based) that

remains after drying or set. The particles bond to each other and to the substrate, providing the desired barrier. Includes the color pigment. — Solvent – this prevents the setup of the binder prior to

placement. It evaporates during drying. — Setup is reversed by readding solvent (even from the next coat

— Catalyst – some coatings (e.g., epoxies) set when a cata lyst is

added or it is heated. — Cannot be reversed

— Thinner – sometimes added to promote flow of the coating. — Too much undermines development of a continuous coating — Use only within the manufacturer’s guidelines — May be necessary for spray applications RE/Coatings-11

Types of Coatings 

Common coatings include — Alkyds – Dries rapidly, hard and durable, poor alkali and fair

petroleum solvent/oil, good water resistance — Oil base – Natural and organic hence va riable, tends to yellow, dries slowly, durable, may be brittle and prone to crack. Less used due to VOC’s. — Phenolic resins – Good flexibility, chemical resistance,

durability. Yellows. — Epoxy esters – Dries rapidly, durable, good ch emical/moisture

resistance, moderate alkali resistance.

— Vinyl resins – Dries rapidly, durabl e, excellen t acid/alkali/water

resistance, limited to about 150ºF. — Chlorinated rubber– Dries rapidly, durable, excellent

acid/alkali resistance, fair petroleum oil/solvent resistance, dissolved by aromatics. RE/Coatings-12

Types of Coatings — Catalyzed epoxy – Durable, good alkali/water/non-

organic acid resistance, poor organic aid and salt resistance. Sets by a catalytic action.

— Acrylic – Good chemical resistance, stable color, bake to

give a hard finish. — Latex – water based, poor chemical resistance, relatively

non-hazardous, poor durability, usually requires several coats. — Galvanizing — A zinc based coating applicable to carbon and low alloy steel. — It must not be used on, or be applied near, stainless steel because

of liquid metal embrittlement concerns. — Acts as a barrier and provides anodic protection (zinc becomes

the anode). As such, small gaps or flaws are much less of a concern (“self healing”). — May be applied by dipping or by heating zinc ‘dust’ sprayed on RE/Coatings-13

System Selection Considerations 

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In many refineries standard coating systems and preferred or required suppliers have been determined All of the coating materials (primer, intermediate coats, top coats) should come from the same supplier — If any part of the coating fails, the entire coating fails — Minimizes the potential for compatibility problems — Eliminates many of the responsibility issues should the

coating fail 

Environment category

— PIP suggests four categories, moderate, severe,

severe/seacoast, and offshore

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System Selection Considerations 

Metallurgy and equipment — Carbon/low alloy steel or stainless steel — Coatings for stainless steel must be free of halogens

(e.g., chlorides), zinc, sulfur, etc — Insulated or uninsulated — Structure, vessel, piping, tank, heater/stack 

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The atmosphere to be resisted (chemicals, heat, moisture) — Moisture and corrodents can be trapped beneath insulation or fireproofing – concrete fireproofing can even provide moisture) Safety and regulations (e.g., exposure to volatile organic compounds (VOC’s), flame spread, odor) Life (target at least 10 years) — Elevated temperature services may be limited by the

available materials

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System Selection Considerations

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Life cycle cost (installation + maintenance cost over it’s life). This accounts for coating materials, coverage, surface preparation, application, durability, ease and frequency of maintenance.

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Ease of application.

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Potential for abuse.

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Color – many plants have a color code to identify the content of piping (e.g., blue for cooling water, white for steam) and standard colors for other applications. RE/Coatings-16

System Selection Considerations 

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In-service access, e.g., coatings under insulation or fireproofing cannot be observed Surface requirements (e.g., roughness for slipcritical structural connections) Special uses — Temperature indicating paint (turns colors to

indicate target temperature was exceeded) — High emmissivity (where infrared temperature measurements will be taken — Buried (exposed to organic corrodents, water, etc.) 

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PIP CTCE1000, “External Coating System Selection Criteria”, provides some guidance Utilize an expert for unusual situations RE/Coatings-17

System Specification 

Specification of a coating system includes — Extent of the coating — Surface preparation (e.g., SSPC SP-5) and the

required anchor profile (in mils) — Coats to be used (primer, topcoat, etc) — Materials used for each coat (e.g., category, such as alkyd, and brand name) — Dry film thickness (DFT) of each coat (minimum and maximum, in mils) — Method of application (brush, roller, spray) — Time between coats — Special instructions beyond the manufacturers

requirements (e.g., temperature, mixing etc) 

See Attachment D for an example from PIP RE/Coatings-18

Surface Preparation 

The condition of the surface to which the coating is applied plays a major role in the condition, durability, and life of the coating. — Application over loosely bonded rust, oil, paint, etc will

result in coating failure. — Application over mill scale in an elevated temperature

service may result in failure because the mill scale expands differently than the metal and may disbond. — Steel and mill scale also form a galvanic cell, with

the steel as the (corroding) anode. — Application over water or other impurities that are

absorbed into the coating damage the coating’s chemistry or, in the case of water, produce flaws in the lining as the water dries.

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Surface Preparation — The surface roughness, or anchorage, must be

proper coating chosen. Too rough or too smooth for arethe both a problem. — Sharp edges, rough welds, etc produce very

difficult areas to adequately coat. The coating is thin and may even un off the surface, leaving an exposed edge.

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Coatings can be placed over tightly adhered existing coatings if the coating materials are compatible.

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Surface Preparation 

Surface preparation requirements are specified by calling for the appropriate SSPC surface preparation (SP) method from the following list: — SP-1, Solvent Cleaning – uses a solvent followed by a

fresh water wash to remove all oil, grease, paint, dirt, etc. Often use prior to one of the following methods. — SP-2, Hand Tool Cleaning – cleaning with a brush, scrapper, hand chisel or similar tool. — Doesn’t remove tightly adhered material. — Slow and inconsistent, only considered for small areas. — Potential to damage the substrate. — SP-3, Power Tool Cleaning – cleaning with an impact scraper, chisel, or rotary power tool. Similar concerns to SP-2, though results are more consistent. RE/Coatings-21

Surface Preparation — SP-5/NACE No 1, White Metal Blast Cleaning – blasting

with a high pressure abrasive stream until all mill scale, corrosion products and other foreign matter are removed. — Costly, used only for severe and immersion services. — SP-6/NACE No 3, Commercial Blast Cleaning - blasting with a high pressure abrasive stream until all mill scale, corrosion products and other foreign matter are removed, except for random, defined, staining over less than 33 percent of the surface. — Used for mild conditions. — SP-7/NACE No 4, Brush-Off Blast Cleaning - blasting with a high pressure abrasive stream until all loose mill scale, loose corrosion products and other foreign matter are removed. — Tightly adhered materials (cannot be removed with a dull putty knife after blast cleaning) remain. — Applicable to touchup. RE/Coatings-22

Surface Preparation — SP-8, Pickling –cleaning and removal of contaminants by

immersion in an acid (or alkali) bath. — Heavy deposits are often removed first by of the other methods. — Take care not to redeposit contaminants when removing from

the bath — SP-10/NACE No 2, Near-White Blast Cleaning - blasting with

a high pressure abrasive stream until all mill scale, corrosion products and other foreign matter are removed, except for random, defined, staining over less than 5 percent of the surface. — Used for moderate to severe service

— SP-11, Power Tool Cleaning to Bare Metal – cleaning with a

[power tool until all mill scale, corrosion products and other foreign matter are removed, except for slight residue left in the bottom of pits, if the srcinal surface was pitted. — SP-12/NACE No 5, High Pr essure Water Jet C leaning – Blast cleaning with high pressure water — Include an inhibitor to retard rustback —

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Surface Preparation 

Blast cleaning uses abrasive grit — Sand was commonly used, but is rare now due to concerns

with silicosis if the sand breaks into a fine dust

— Metallic grit and other silica free media (e.g., steel shot, even

walnut shells) are now used — Grit must be “sharp”, i.e., rough, clean, and dry — Reuse of grit may be permitted if it is still sharp, and the

products of previous blasting have been removed — Grit for stainless steel blasting must not contain carbon or

low alloy steel or any other detrimental materials (e.g., chlorides and other halogens, zinc, etc). Equipment must be completely free of these materials too – use dedicated equipment RE/Coatings-24

Surface Preparation — Grit may remain embedded in the metal. If so, it must be

compatible with the coating system and be completely covered by the coating. — SSPC has several documents addressing grit requirements — AB-1, “Mineral and Slag Abrasives” — AB-2, “Cleanliness of Recycled Ferrous Metallic Abrasives — AB-3, “Newly Manufactured or Re-manufactured Steel Abrasives 

Blast cleaning removes contaminants and leaves a surface profile suitable for coating — Roughness depends on the coating, 1-2 mils (25-50µm) is

typical — Too smooth leaves insufficient roughness for primer to adhere — Too rough may leave hard-to-coat edges or project trough the coating — Profile is measured per ASTM D4417 or NACE 0287 RE/Coatings-25

Surface Preparation 

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Do not blast clean if the humidity is high or the surface temperature is within 5ºF (3ºC) of the dew point. Protect stainless steel from blasting of any carbon or low alloy steel. Immediately after cleaning, all cleaning products, dust, blast residue must be completely removed by blowing with clean, dry air, brushing/sweeping or vacuuming. The surface must be dry. Do not wash with water. Coating must occur the same day as the cleaning. The first layer of coating must be applied before any ‘rustback” or other damage occurs. — Soluble salts accelerate rustback. Check using SSPC

YU-4 or, when applicable, SSPC-12/NACE No 5 RE/Coatings-26

Application

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Each coat must be applied to the specified minimum thickness, which normally is between 1 and 5 mils (25 and 125 µm). Occasionally a maximum will be specified too. — If too thin, a continuous barrier may not be formed.

Thickness must be adequate for the binder particles to align and form continuous coverage. — If too thick, proper drying may not occur and the coat

may run. — Special attention must be paid to sharp edges, welds, and other hard to coat areas. They do not hold the coating well, and it will tend to run off, leaving a thin, or non-existent coating. RE/Coatings-27

Application

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Coatings may be applied by brush, roller, or spray (air or airless)

— Acceptable application methods and cautions will be

provided by the coating manufacturer — Application rates are approximately — B r us h

1000–1 500ft 2/day (93-140 M3/day)

— R o l ler

2000–4 000ft 2/day (185-370 M3/day)

— A ir S p ra y

4000 – 8000 ft 2/day (370-740 M3/day)

— Airless Spray 8000 – 12,000 ft 2/day (740-115 M3/day)

— Use spray coating whenever practical (overspray is

a concern) RE/Coatings-28

Application 

Brush Application — Affected by brush size, shape, bristle shape and material — Best for limited and uneven areas, coating around

obstacles, and for working into cracks — Coat edges, high points, hard to reach points before use of another method for the bulk of the surface 

Roller Application — Rate and quality affected by roller size — Affected by nap length, roughness, and material — 3/16 to 3/8 inch (5-10mm) nap for smooth surfaces — 3/8 to ¾ inch (10-19mm) for medium surfaces — ¾ -to 1¼ inch (19-32mm) for rough surfaces — Splatter is a concern — Not used on irregular surfaces (e.g., bolts, corners, sharp

and double curvatures)

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Application 

Spray — Coating is atomized by air or pressure and

projected onto the surface — Used on large, open surfaces — Concerns are safety, overspray, splatter and waste — All stainless steel that may be reached by coating of a

non-stainless surface – especially for coatings containing zinc or chlorides (halogens) must be covered or protected (may be a concern with any means of application)  Consider wind direction and velocity 

Consider gravity effects

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Often cover everything within 100 feet (30 meters) and anything below the sprayed area RE/Coatings-30

Application

— Ensure there is no oil contamination in an air spray — ASTM D4285 provides one method — A cloth over the gun while “spraying” only air is a

simple method — Airless sprays compress only the paint under very

high pressure (500 – 3000+psi (35-210+ kg/cm 2)), atomizing it — Better coverage because there is no air rebound

interfering with placement and causing paint rebound and loss

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Application 

Many coating systems use a primer and a topcoat, some include an intermediate material or two — Primer — Typically 1.5 – 2.5 mils (38-64 µm) thick (to cover the

surface anchorage (roughness)) — Coats/protects substrate and provides surface for upper coat adherence — May be the only protection during shipment (exposure to abuse, sea air, etc) — Inorganic zinc is common — Topcoat — Typically 1.0 – 2.0 (25-50 µm) mils thick — Color and appearance are important — Exposed to the operating environment

— Color or tint of each coat shall differ from the

neighboring coat(s) to provide a visual indication of coverage RE/Coatings-32

Application 

Subsequent coats are applied after the lower coat has set up but while it is still receptive to bond with another layer. This is called the recoat interval.

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Multiple coats of the same material can be placed, but development of the full thickness of the coat in one pass is most economical, if an acceptable coating results. Ambient and substrate temperatures to be within the limits set by the manufacturer during application and cuing. Normal temperatures are between 50ºF (10ºC) and 100 (38) (sometimes 120(49)) ºF (ºC). Do not apply coating if the temperature is less than 5ºF (3ºC) above the dew point (condensation forms on surfaces cooler than the dew point) or if the humidity is outside the specified range (condensation and/or slow drying.

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Application

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Do not apply coating in wet weather, fog, or if the

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surface is wet Do not spray in windy weather (over 15 or 20mph (25 or 30kph))

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Coating to stop at least 6 inches (150mm) from where welding will occur (inorganic zinc primers may be closer)

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For repairs and recoating, feather the new coating into the existing material to avoid the creation of high, or rough spots

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Application 

Hazards — Vapors may be hazardous (VOC), provide plenty of

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— —

— —

ventilation. — Be sure air is well circulated to all areas. Solvents and other components are often flammable. Keep flame or sparks away. Ventilate to remain below the flammable limit. Contact and splashing. In some cases hazardous chemicals (e.g., lead, chromium compounds) may be encountered, particularly during removal of old coatings (this may be the most hazardous period). Consider any cautions contained in the MSDS’s. Follow the manufacturers recommendations. See also guidance in SSPC PA-3. RE/Coatings-35

Application

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Several documents provide guidelines for application — PIP CTSE1000 – Application of External Coatings — SSPC PA-1, Paint Application Specification No. 1,

Shop, Field, and Maintenance Painting of Steel — SSPC PA Guide 3, Paint Application Guide No. 3, A

guide to Safety in Paint Application — SSPC PA Guide 4, Guide to Maintenance Repainting

with Oil base or Alkyd Painting Systems — SSPC PA-COM, Commentary on Paint Application

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Inspection 

The entire coating system must function properly, otherwise it fails — Each coat must be properly bonded — Must not be any gaps through the lining — Even a small gap allows corrodents access to the substrate

Substrate becomes a small anode, coupled with a large cathode, leading to rapid corrosion — Edges and other hard to coat areas can become gaps 

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Documents that provide guidance for inspection include — SSPC-PA 2, Measurement of Dry Coating Thickness with Magnetic

Gauges — Type 2 works with nonmagnetic materials (e.g., austenitic stainless steel) — SSPC-VIS-1-89, Visual Standard for Abrasive Blast Cleaned Steel — SSPC-VIS-3, Visual Sta ndard for Powe r- and Hand-Tool Cleaned Steel — NACE Standard RP0188, Discontinuity (Holiday) Testing of New Protective Coatings on Conductive Substrates RE/Coatings-37

Inspection 

Inspection — Primarily visual — Measurement of the wet and dry film thickness. — Dry film thickness is most important because it

is indicative of the coating performance — SSPC PA-2 describes the common methods — Check for oil contamination — Black light (will reveal contaminants) — Wipe with a clean cloth (stains cloth) — Sprinkle with water (it will bead) — Check for discontinuities — “Sponge” or “Spark” Test per NACE RP0188

is commonly used RE/Coatings-38

Inspection 

Where problems are found, new coating materials can be placed over the existing material if — The existing material is clean and well bonded to the

substrate — The materials are compatible (same manufacturer is best) — The surface anchorage of the existing material is adequate

(roughening is acceptable) 

Remove coatings that are loose, cracked, brittle, improperly mixed, oil water, or foreign material contaminated, or catalytically set materials missing or using the wrong catalyst. — Material can be removed in accordance with the surface

preparation methods described earlier and the area recoated — Remove coating at least 2 inches (50mm) beyond the damaged area — Feather any joint with neighboring coating — Recoat with same, or compatible, material

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Damage Mechanisms 

Following are indication of an ineffective coating — Holidays – An opening in a protective coating that

exposes unprotected surfaces to the environment. Includes cracks, pinholes, thin spot, foreign material/contaminant

— Alligatoring – irregular cracking network in a pattern

similar to an alligators skin. May be due to topcoat added before undercoat is set, leading to shrinkage stresses in the top coat when the undercoat does set. Also called mud-crackin — Edges – edges, welds, embedded grit, etc are difficult

to coat and may have little or no coating RE/Coatings-40

Damage Mechanisms — Blisters – bubbles of air, moisture or solvent

trapped in the coating. Will break and provide an opening in the coating — Thick coats can trap air — Upper coat placed before lower coat solvent has

escaped (e.g., high lower cat solvent content — Runs – Coating drops or droplets dripping down

the (vertical) surface — Sags – Droop of the coating leaving a thick lower

edge due to excessive material placed in one pass or, occasionally, too high of an application temperature. Also called curtaining.

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Damage Mechanisms — Bleeding – lower coat pigment shows through — Upper coat is to thin — Upper coat solvent has dissolved, and absorbed

some of the lower coat — Lapping –visible portion of neighboring coating

applied over freshly applied coating due to rapid drying and/or too little coating “flow out” — Wrinkling – Non-planar surface – Top dries while

the lower part is still soft due to too thick a coat — Blushing – white film on the surface due to water in the coating — Chalking – minor surface flaking (powdering) of the

coating – usually due to wea ther factors RE/Coatings-42

Damage Mechanisms — Peeling – coating does no t stick. Due to — water or oil in the coating — incompatible materials — improper surface preparation — primer damaged by top coat solvent — application outside of the recoat period — contaminant fallout (spray) of from nearby items

onto the surface to be be coated — Mildew – Organic fungal growth on components — Can add a “mildewicide” but that may not

prevent growth in deposits on the coating surface RE/Coatings-43

Damage Mechanisms — Cracking – break through in the coating to the next coat

or the substrate due to excessive coating shrinkage, or thermal expansion of the substrate beyond what the lining can tolerate — Checks – shallow cracks that do not penetrate to the lower coat or substrate — Pinholing – small openings through the coating — solvent lost in spraying leaving too little for the binder to flow — evaporation of entrained water — burst blister — substrate high points or embedded blasting grit — local coating breaks due to tension RE/Coatings-44

Damage Mechanisms — Insufficient dry film thickness – too little solvent or

binder, or insufficient thickness for the binder to flow and fully coverfilm the substrate — Gelling – Coating begins to set up before application,

even in the container — Lack of set in catalytic materials – wrong or missing

catalyst — Mechanical Damage – Handle the coated item by

means that will not damage the coating (e.g., slings), do not drag, use chains, etc.

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Insulation

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Insulation 

In this section describes the primary purpose(s) of external thermal insulation, and the common forms of insulation used in refineries

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Insulation 

Reference materials — ASTM standards provide requirements for

categories of insulating materials (e.g., calcium silicate)

— PIP (Process Industry Practices) Provide

guidance on insulating systems and use — See Appendix A for a more extensive listing of

these standards

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Insulation 

Insulation Uses: — Conservation of heat within the piping, vessels,

equipment and ducts

—Minimize heat loss and/or maintain the desired

temperature in the piping and equipment (Process considerations) —To minimize the heat loss (Economic considerations) 

Compares insulation costs with the cost of energy (fuel) over the life of the insulated item

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A transient target because energy costs constantly change

— Safeguard personnel (Personnel Protection) RE/Coatings-49

Insulation

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Insulation Uses — Prevent the condensation due to cold fluid in

piping or equipment (Freeze Protection)

— Noise reduction (Soundproofing- e.g., compressor

shelters)) — Fire Protection — Steam and Electric Heat Tracing (Prevents

viscosity increase or freezing of contents, retains heat from the heating medium) 

Insulation is a system, not a material. It includes a thermal barrier, equipment coating, weather proofing, and the means of installation RE/Coatings-50

Materials 

Common Insulating (thermal barrier) Materials — Calcium Silicate — Mineral Fiber Pipe Insulation (Preformed) — Mineral Fiber Blanket — Mineral Fiberboard — Molded Expanded Perlite — Cellular Glass Pipe and Block

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See Appendix E for relative strengths and weaknesses

RE/Coatings-51

Materials 

Prior to 1960 asbestos was a common component, occasionally the primary component. Insulating materials are now free of asbestos.

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Calcium Silicate was the most commonly used material for many years. — For areas prone to mechanical damage, Calcium Silicate is

still preferred because of its rigid, hence rugged structure 

Mineral wool and perlite are now the materials most often used. — Less permeable to water absorption — Lighter weight thus lesser cost for installation and support — Calcium silicate must be purchased and/or cut to size to fit

the insulated object 

Cellular Glass is more commonly used for cold services. The insulation minimizes condensation and cellular glass does not absorb water. RE/Coatings-52

Materials

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When insulating stainless steel, the material(s) must be chloride free to eliminate the potential for stress corrosion cracking — For stainless steel piping, insulation conforming

to ASTM C795 is used to deter the affect of stress cracking of free moving chlorides from insulation — Calcium Silicate contains free moving chlorides

and is detrimental for covering stainless steel

RE/Coatings-53

Thickness

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The required thickness depends upon the thermal conductivity of the system chosen ASTM C680 provides a method of determining the heat flow and predicting the temperature(s) within an insulated system — There are many commercial programs available

from suppliers and elsewhere (e.g., 3E Plus (NAIMA-North American Insulation Manufacturers Association)), most are based on C680 

Other sources (e.g., textbooks) have empirical formulas for defined circumstances RE/Coatings-54

Weatherproofing

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Weatherproofing is applied on the top of insulation to protect the material from damage (abuse) and weather. An important function is to prevent the entrance of moisture into the insulation. — Insulation depends upon trapped, stagnant, pockets

(hence no convection) and low conductivity material to perform. If it gets wet, water. —Fills voids and is a good heat conductor —Compresses the material, reducing/eliminating

the pockets —Contributes to base metal corrosion —Can dissolve insulation binders RE/Coatings-55

Weatherproofing 

Metal jackets are used on the top of insulation as weatherproofing. —Jackets are aluminum, steel, stainless steel, or plastic.

Aluminum and stainless steel are the most common. —Metal jackets may be smooth or crimped depending

upon the size of pipe or equipment and the potential for abuse. Crimped jackets are stronger and more rugged. In potential abuse areas the jacket must always be steel or stainless steel. —When the insulation is used for fireproofing, the metal

jacket shall always be stainless steel. Stainless steel will not melt in a fire and can withstand the impact of water from a fire hose. 

Metal bands are used on the top of jackets for securing purpose. RE/Coatings-56

Insulation Installation

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Insulation is to be by experienced personnel.

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Insulation is installed in single or multiple layers depending upon the thickness. Generally over 3 inches (75mm) thick, multi layers insulation is applied.

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Joints (seams) of layers are overlapped (offset) to prevent a path through the insulation.

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Provide expansion joints on piping insulation to accommodate axial thermal growth.

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External stiffeners must be fully insulated to maintain a temperature equivalent to that of the vessel. RE/Coatings-57

Insulation Installation

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Insulation is supported by rings on the vessel. The rings are loosely supported by lugs welded to the vessel. The rings must be allowed to slide on the lugs to accommodate the vessel’s thermal expansion.

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For soundproofing insulation, all bolts, bands, etc must be firmly fixed into place to prevent vibration and/or loosening.

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The insulated item must normally be primed and/or painted to prevent corrosion beneath the insulation, especially if it operates below 212ºF (100ºC).

RE/Coatings-58

Insulation Installation

Steam Tracing

Vessel Insulation Support Rings RE/Coatings-59

Insulation 

When to consider not insulating — When flanges were selected based on an

uninsulated temperature (normally for service temperatures over 800ºF (425ºC))

— Flanges in toxic or severe cyclic services (to

permit detection of a leak) — Flanges in hydrogen service (to detect leaks) — Piping or equipment where heat loss is

intentionally desired

RE/Coatings-60

Weathershielding



Weathershielding — Weathershielding is protection via a metallic

barrier — Used to protect items from abuse or the elements,

while retaining the temperature drop applicable to uninsulated components — Normally designed to promote a draft, or air flow

RE/Coatings-61

Weathershielding

RE/Coatings-62

Personnel Protection 

Personnel protection is insulation applied near traffic areas to prevent personnel contact with hot surfaces. The remainder of the object may be uninsulated.



Personnel protection is typically provided on surfaces exceeding 140ºF (60ºC). The protection may be — Insulation — Barrier (e.g., a screen) to prevent contact

RE/Coatings-63

Fireproofing

RE/Coatings-64

Fireproofing



This seminar introduces the basic requirements for and means of providing fireproofing within a refinery.



The attendee will understand where fireproofing may be required and what materials may be suitable.

RE/Coatings-65

Fireproofing 

The term “fireproofing” is misleading in that it’s not “proof”. It retards the heating rate of the underlying material in the event of a fire, hence exposure to high temperatures. The intent is to prevent structural collapse and the release of flammable materials.



The systems and methods covered in this seminar are passive (the system protects without action or intervention) with the possible, technical, exception of intumescent and maybe subliming systems.



Fireproofing of refinery structures and equipment is covered by API 2218, “Fireproofing Practices in Petroleum and Petrochemical Processing Plants”. Includes means of determining fireproofing needs and provision. A section of questions and answers is included at the back. RE/Coatings-66

Fireproofing 

Fireproofing is to be provided within the fire scenario envelope in accordance with relevant standards. API2218 defines it as 

   



A three dimensional space around fire potential equipment or items containing nonflammable hazardous materials near fire potential equipment 20 - 40 feet (6 – 12 M) above 20 – 40 feet (6 – 12 M) to either side of fire potential equipment The fire is normally considered to be at grade Fireproofing may be carried to major elevated equipment (e.g., FCC Reactor) and air coolers and their supports

Fire Potential Equipment is equipment where a leak or is likely and/or an ignition source is nearby    

Fired Heaters, boilers and incinerators Pumps Compressors Equipment containing flammable material

RE/Coatings-67

Fireproofing 

The ability of fireproofing to protect underlying members is measured by — UL 1709, “Standard for Rapid Rise Fire Tests of

Protection Materials for Structural Steel”. This is the test most applicable to hydrocarbon fires — ASTM E119, “Method for Fire tests of Building

and Materials” was used in wood) the past,Construction but it is for building materials (e.g., and the rate of temperature increase and the ultimate temperatures did not match those in a hydrocarbon fire RE/Coatings-68

Fireproofing 









Fireproofing must withstand the heat of a fire without damage, and protect the underlying material for a predetermined minimum time (usually 1.5–3 hours) called the fire resistance rating. Fireproofing is generally applied to structures and piperacks within fire scenario envelope. Equipment, other than supports (e.g., skirts) is rarely fireproofed. Many vessels are insulated, which provides some protection. Fireproof columns, major beams, and bracing contributing to equipment support. Wind bracing may not be fireproofed (sometimes alternate bays are fireproofed), though its stabilizing effect on the columns must be considered. The top surface of beams is typically not fireproofed because floor plate/grating, equipment, etc rests on this surface. Apply fireproofing after all construction is complete so all connections are protected.

RE/Coatings-69

Fireproofing 





Fireproofing must remain in place, with minimal maintenance, yet function when needed Materials must withstand mechanical and atmospheric (weather and contaminants) abuse over their lifetime, including freeze/thaw cycles, thermal gradients during a fire, and the force of firewater application Life of 10 years or more with low/no maintenance

RE/Coatings-70

Fireproofing Materials Methods of providing fireproofing include — Concrete — Heavy (150 pcf (2400kg/M3)) — Rugged, durable. Can withstand hose stream impact

and flame impingement — Time consuming to install, requires forming — May “box” structural members or follow their

contours. Requires a reinforcing mesh — Easily inspected and determined to be in place,

covering the protected material and ready for service — Permanently seal the ends of the fireproofing

(especially the upper end on columns) to prevent water entry. Provide a drain at the bottom

— Steel must be primed to protect against corrosion — Damaged, even destroyed, by major corrosion of the

underlying steel RE/Coatings-71

Fireproofing Materials — Light weight concrete — Lighter than concrete ( less than 80 pcf (1280

kg/M3)) — Less rugged than concrete — Better insulator than concrete, hence less

thickness is required — Must be coated or protected to prevent moisture

ingress (freezing can spall the concrete) — Otherwise similar to concrete

— Lightweight cementitious material — Made of Portland cement and very lightweight

aggregate (40 – 50 pcf (6 40-800kg/M 3)) — Similar properties to lightweight concrete RE/Coatings-72

Fireproofing Materials 

Intumescents — Applied as a thin coating, sprayed or painted. May be difficult

to ensure full coverage

— When exposed to heat, swells to many times their srcinal

volume, with many contained voids to provide insulation — May be mastic or epoxy based – epoxy is generally more suitable (it bonds to the subsurface and is flexible) — Protected material must be coated before application — May need weather protection, reinforcing, and/or a surface sealant — Minimal extra weight — Degree of protection, especially in complex geometries, is questionable. Cannot be sure (in advance) that they will work as intended when exposed to heat — Can be damaged RE/Coatings-73 — Re uire ex erienced, s ecialt a licators

Fireproofing Materials 

Subliming materials — Absorb heat to vaporize from a solid directly to a vapor phase without a temperature increase. — Solid phase allows application as a coating. — Prevents a temperature increase of the underlying

material until it is gone. — Subject to damage from abuse (can be scraped off). — Gaps expose the underlying material to high

temperatures. Small gaps may be difficult to detect. — Otherwise similar to intumescents. 

Ablative Materials — Absorb heat via oxidation erosion of the material. — Otherwise similar to intumescents.

RE/Coatings-74

Fireproofing Materials



Insulation — Fibrous material — Forms an insulating layer with many contained air

pockets to resist the transfer of heat — Sprayed on or installed in preformed blocks or blankets — Easy to miss areas, leaving some material unprotected — Easy to damage, may blow off or wash off in rain. Must be kept dry — Best suited for enclosed, protected areas (e.g., inside a wall) — Lightweight RE/Coatings-75

Fireproofing

RE/Coatings-76

Fireproofing

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Monolithic Refractory

RE/Coatings-78

Refractory 

This section discusses the primary types, functions, and installation of monolithic refractories

RE/Coatings-79

Refractory 

Sources of information — API 936, “Refractory Installation Quality Control

Guidelines – Inspection and Tes ting Monolithic Refractory Linings and Materials” — There is an API certification program based upon API

936 — Process Industry Practices (PIP) – A family of practices for

refractory will be issued, beginning in the spring of 2004. See Appendix A — Refractory manufacturer’s websites — ASTM Standards for testing of refractory properties (see

Appendix A for a listing)

RE/Coatings-80

Refractory 

Resisting control or authority: Stubborn

 

Resistant to treatment or cure Immune



Unresponsive to stimulus



Difficult to fuse, corrode, or draw out.

Refractories are materials that maintain their functional ability (are stubborn) under, and are unaffected by, stressful conditions. They may be a concrete like castable, ceramics, bricks, etc. RE/Coatings-81

Characteristics of Refractory



Volume Stability —Does not shrink, deform, or creep significantly at

process temperature and conditions.



Functional Ability —Performs required function(s) at process temperature

and conditions over desired time period (durable). 

Cost Effectiveness —Best measured as a life cycle cost, including

maintenance and repairs, not a capital cost to install.

RE/Coatings-82

Refractory Properties 





Values for properties are listed on data sheets produced by the manufacturer. Typical properties listed are cold crushing strength, modulus of rupture, density, chemistry, permanent linear change, thermal conductivity, and abrasion resistance. Values are for quality control purposes, not design, and are often unreliable. in part because their basis is unknown. Obtain guaranteed values from the manufacturer with which to compare test r esults. Compliance Data Sheets as specified by API are available for this purpose. RE/Coatings-83

Function

Refractory Property*

Insulation

Porosity, Low Density, Shock Resistance (low thermal expansion or conductivity)

Load Bearing

Strength

Resist Abrasion

Hard, Dense

Resist Chemical Attack

Chemical makeup and stability, inert, low permeability

Contain Fluid

Density, low permeability, no cracks



Often, multiple functions are desired. Frequently, the necessary properties are in conflict and compromises must be made. *Required properties are at operating temperature and conditions–available data sheet properties are averages at ambient temperature. RE/Coatings-84

Refractory Use in Refineries



Purpose —Internal insulation (allows use of thinner shells

of less expensive alloys) —Abrasion resistance (protects the underlying material from erosive environment) 

Installed In —FCC Units (reactor/regenerator system) —Hydrogen Units (transfer lines) —Reformers (reactors) —Thermal Hydrodealkylation Units (reactor) —Heaters —Other hot or abrasive environments RE/Coatings-85

Abrasion Resistant Linings 

Thin - 3/4 to 1 inch (19 to 25 millimeters)



Very dense and hard (up to 190 lb/ft3 (3040 kg/M3)). High conductivity, unsuitable as an insulator (conductivity is influenced by the anchorage system used, i.e. amount of metal present and contact–for conduction–with shell).





May be porous and permeable. Not suitable to protect the shell from the internal environment. Shell may corrode beneath refractory and cannot be inspected. Absorbed materials may be released after shutdown, a potential hazard.

RE/Coatings-86

Hex Mesh Anchorage   

 





Normal method of anchoring abrasion resistant lining. Large, continuous pieces. Welded to shell frequently, especially in severe service. Edges must be securely welded. Installation is slow. Difficult to form to curved surfaces, roll the “hard” way. Cannot be double curved. Failures are normally failures of the weld to the shell. Continuous sheet allows other welds (redundancy) to hold the hex in place. Refractory failures confined to individual hexes—usually consider replacement at next TAR if ½ depth is eroded. —Consider how long it took to erode to ½ depth —Further erosion may result in little holding the biscuit RE/Coatings-87

Hex Mesh and Anchorage

Note the differing weld patterns for coking vs. non-coking environments. The “tabs” projecting into the biscuits are intended to provide mechanical anchorage to the refractory RE/Coatings-88

Individual Anchors 

Also called “Hexalts”.



Many types on the market including S-Bars (accepted for non-coking service) and hex cells (accepted for coking service). Three point, non-planar, system is best.



Easier to install then hex mesh. Can conform to curved surfaces because forming is not needed.



Usually used only for sharply or double curved surfaces



and for limited repairs. Requires fibers in the refractory.



Non-continuous system. Failures tend to be localized. Material can fall off and be carried downstream. RE/Coatings-89

S-Bars and Anchor Pattern S-Bars are not approved for coking services

RE/Coatings-90

Hex Cells and Anchorage Pattern

Many kinds ofThey “hexalts” are available. may be used for coking services.

RE/Coatings-91

Corner Tabs 

Corner tabs are used when the refractory goes around a corner



Fixed corner tabs are used for 90 degree corners — They’re available at

other, fixed, angles too 

Variable tabs allow adjustment for any angle joint

RE/Coatings-92

Insulating Linings 

   

Consist of two parts—the refractory and an anchorage system of individual anchors. Thick—at least 4 inches (100 millimeters). Lightweight. Soft and Porous (but not permeable). Low Thermal Conductivity. —Effective conductivity will be greatly increased in

hydrogen atmospheres. —Catalog conductivity's are normally much lower than actual field values. —Conductivity is very difficult to reliably measure and is very sensitive to the actual refractory conditions. RE/Coatings-93

Insulating Linings 



Shell temperature to be greater than the dew point of the contained vapors (including water vapor). Often include and steelprevents fibers for crackfrom control (reduces crack growth pieces falling out). Does not prevent crack initiation or significantly affect material properties. —3/4” or 1" (19 or 25mm) long, 20 mil ((508µm) thick —304SS melt extract or deformed —Fibers must be uniformly distributed and randomly

oriented



Typically use the following weight percents. —4% for gunned installations —3% for rammed installations —2% for cast installations RE/Coatings-94

Prediction of Shell Temperature 

Accurate prediction of the shell temperature behind an insulating lining depends upon accurate input information, and/or a means of correlation to operating experience.



Thermal conductivity coefficients are based upon lab samples and testing - not insitu material with unknown properties due to vagaries of the installation process, water remaining in the lining, coke in the lining, and on site conditions.



Catalog thermal conductivity's are unreliable.



Test methods differ, giving different results. RE/Coatings-95

Insulating Lining Anchors



Anchors are placed rows over the surface. —Anchors may be alternately oriented —Anchors may be staggered or in a square pattern







Anchor spacing is approximately twice the lining thickness, closer for overhead installations. Numerous anchor styles are available, V anchors at most commonly used. Anchors are 304 stainless steel, ¼ inch (6 millimeters) in diameter. Anchors larger than 5/16 inch (8 millimeters) may fail at the bend(s). Solution annealing improves anchor endurance. RE/Coatings-96

Insulating Lining Anchors 

Anchor legs do not extend to the lining surface, and may be unequal length to reduce the possibility of creating a shear plane.



Some operators do not use coatings or caps on the anchor legs. Some users include coatings or plastic caps on the ends of the legs to address punching.



Some anchors have a “foot” for welding—gives length for welding and helps orient the anchor to surface. Do not weld at anchor bends—can cause cracks.



Welders must be qualified to weld to the backing item (e.g., Code qualified for a pressure vessel). RE/Coatings-97

Insulating Lining Anchors

These details apply to linings over 2.5 inches (65mm) deep. Note that the anchors have a “foot”. The weld is only on the outside of the “foot” and that it avoids the sharp bent to the vertical. RE/Coatings-98

Insulating Lining Anchors

These patterns to linings greateranchor than 2.5 inchesapply (65mm) deep, using the anchors on the previous slide.

RE/Coatings-99

Insulating Lining Anchors

These anchors and details apply only to linings less than or equal to 3 inches (75mm) thick.

RE/Coatings-100

Dual Layer Lining 

Uses a layer of abrasion resistant material over an insulating material. Now in (strong) disfavor, may be seen in older equipment or Reformer service.



Layering two dissimilar materials, with different anchoring systems, presents many problems. —It’s difficult to install, dry, and inspect. —Upper layer anchorage is poor, allowing distortion. —Lower layer may be exposed to abrasion, which it cannot

withstand. —Cycling is especially detrimental. —Requires frequent maintenance and repair. 

Single component, multipurpose materials are commonly used. Densities are between 110 and 140 pcf (1760 and 2240kg/M3). RE/Coatings-101

Liners   

Used when a catalyst bed is present (e.g., Reformers). Liner isolates the catalyst from the refractory. Provide an expansion joint (allowing for vertical expansion) in the liner. —Locate/design so catalyst does not interfere with

movement of bypass the liner —Provide only one joint so there is not a flow path

behind the liner (i.e., there is no “in” and “out” with a driving pressure drop between them 

Keeps hydrocarbon from the refractory by creating a “dead” area at the refractory.



Liners present their own maintenance problems.

RE/Coatings-102

Cracking 

All refractory cracks.



Cracks caused by permanent linear change (dryout are shrinkage) and thermal expansion. 

Cracks are normal, and desired. They act like an expansion joint, absorbing the refractory’s thermal growth at operating temperature.



In a normal, insulating lining, cracks seen at room temperature close are tight, with the refractory in compression (theand desired condition), during operation. Clean cracks indicate that they close. Dirty cracks, or those with catalyst in them, have not closed during operation.

RE/Coatings-103

Cracking 

Many small, random cracks are best.



Repair cracks that exceed acceptable guidelines (i.e., width, depth, and length), especially those that penetrate to the shell and do not close during operation.



Repair cracks that allow flow behind lining. Remove catalyst, etc. caught in cracks.



Cracks help prevent separation from the shell (undesirable). Too much steel fiber can prevent cracks and promote separation.

RE/Coatings-104

Hot Spots 

Normally indicates circulation behind the refractory. Can be difficult to find because the refractory will often appear undamaged. The gap between the refractory and the shell can close up when shut down for inspection.



Refractory pulls from the shell due to large refractory shrinkage, poor anchorage (too few anchors, poor mechanical anchorage, poor welds), or strong refractory (doesn’t crack).



Can mean a major refractory failure.

RE/Coatings-105

Hot Spots 





At least two cracks are needed (in and out), plus a gap at the shell between the cracks. Must be a pressure drop (e.g. a catalyst bed, baffle, eddy, elbow or tee, flow direction change, etc.) to drive flow behind the refractory. Hydrogen can pass through uncracked refractory and cause a hot spot, especially when there is a pressure gradient and elevated hydrogen partial pressure (e.g., Reformer, Ultraformer).

RE/Coatings-106

Hot Spots 

Concerns are: —Shell gets hotter, expands more, promoting

a larger gap and hot spot growth

—Steel overstress, even failure, tensile or

creep strength at the elevated temperature —In hydrogen service, hydrogen attack

accelerated over time at the greater temperature

RE/Coatings-107

Coking 





Coke forms in refractory voids due to condensation, or due to thermal or chemical reactions. Coke is often present present through the lining thickness. It may also form only in the top ½ – 1½ inch (10-40 millimeters) of the lining. Upon cooldown, coked lining can no longer shrink. Large stresses may be formed. Lining may fracture and spall exposing fresh material for future coking.

RE/Coatings-108

Coking



Coke is normally hard and very abrasion resistant.



Coke may pose little problem to lining for steady state operation. Thermal cycling can cause rapid spalling, if not properly installed.



Coke around hex lining biscuits can cause ratcheting, e.g., extension of FCC risers. It can also “jack” the hex away from the shell, destroying the joining welds.

RE/Coatings-109

Refractory Repair 





Many refractory problems are due to poor installation or cyclic service. Repair is necessary only if the refractory no longer performs its function. A well designed refractory system has a life of 25–30 years or more. Repair does little good if the root cause is not corrected. Hot spots may be externally cooled with air, steam, or water, permanent repair made at the next TAR. —Determine the size of the hot spot with infrared or

temperature indicating paint. —Cool the entire hot spot, and extend beyond its boundaries. —Air is readily available but has a small heat capacity.

Adequate for small gaps and flow behind the refractory. —Steam may be available and has a good heat capacity. Adequate for medium gaps and flows behind the refractory.

RE/Coatings-110

Refractory Repair —Water removes the most heat and is considered for large

gaps and flows behind the refractory. — May not be readily available in the quality and quantity

necessary. — Phase in to avoid shocking the metal, operate continuously. — If metal is eroding it will wear through quickly. Consider an external patch, lined with stellite or other abrasion resistant medium over the entire area of internal flow. The patch is welded to the srcinal metal to contain the fluid and carry the stress if the srcinal pipe holes through. — Injectable mortars often work as a temporary repair, allowing operation until a planed turnaround. 



Smear coats, the surface replacement of spalled areas rarely work, the smear coat spalls upon startup. For a permanent repair, remove the damaged area completely (full depth of lining, extending to good material in all directions).

RE/Coatings-111

Refractory Repair 

Take care to avoid damaging the shell. Linings can be



very difficult to remove, even if damaged. Cut lining perpendicular to the shell.



For large areas on walls, the new lining can be gunned.



For small areas, forms and casting will be necessary. Allow for venting of air (i.e. no pockets or traps).



Flowable or self leveling materials are often used (requires a well sealed form system). Plastics are another commonly used material. Phosbonded refractories have been a “universal” material for very small repairs because it tends to stick to other refractory materials.

RE/Coatings-112

Inspection



External infrared examination and temperature indicating paint during operation to see hot areas during operation - Infrared examinations are every 6–12 months, more at areas of concern



Visually inspect after installation, heat dry, and at each turnaround



Hammer test for voids or weak areas - Hammer tests are unreliable, but are easy and available

RE/Coatings-113

Refractory Selection



What is the service environment?



What is (are) the desired function(s)? —Insulation? —Abrasion resistance? —Etc.





Refractory data sheets—in particular permanent linear change (plc), density, and abrasion loss (per ASTM C-704). Obtain guarantees or properties of supplied material (generally “worse” than data sheet values).

RE/Coatings-114

Refractory Selection 

Ease of storage, handling, and installation.



Availability. Experience with the materials in the same or very similar circumstances is the most valuable guide for refractory selection.



RE/Coatings-115

Questions

RE/Coatings-116