Mounded LPG Bullets - EIL (Ppt)

Engineers India Limited Mounded LPG Bullets – Safety in Design, Construction, Inspection and Operation

National Seminar on ‘Safety in Hydrocarbon Sector : Drilling to Dispensing’ Thursday, September 27th, 2012

L.K. Vijh, Executive Director (Plant Operations & Safety Division), Engineers India Limited

Presentation Plan Introduction to LPG Storage and Transfer BLEVE What is Mounded Bullet !!!!!!!? Design Codes Applicable Facility Sitting

Design Parameters Instrumentation and fittings on vessel Fire and Gas Detection Operation, Maintenance and Inspection

11-Oct-12 Slide No.-2

Introduction LPG is a mixture of propane and Butane with an explosive range of 1.8% to 9.5% in air

LPG is colorless with an thermal expansion coefficient of 0.00237 per °C

LPG due to its inherent properties is susceptible to fire and explosion hazards

The conventional method of storage of LPG in India is in a pressurized vessel installed aboveground. For large volumes cryogenic storage option can be used

11-Oct-12 Slide No.-3

BLEVE Boiling Liquid Expanding Vapor Explosion (BLEVE)

Caused by external flame impinging on the shell of a vessel above the liquid level, weakening the container leading to shell rupture Causes a sudden release of a large mass of pressurized superheated liquid

Superheated liquids flash typically increasing the volume over 200 times.

Results in heavy damage due to fire ball, pressure wave and impact by vessel fragments.

11-Oct-12 Slide No.-4

BLEVE– Incident San Juanico Disaster PEMEX, Mexico, 1984

BEFORE

AFTER

11-Oct-12 Slide No.-5

San Juanico Disaster, PEMEX, Mexico, November 19,1984 8” Pipe rupture occurred near the sphere The Control Room operator tried to identify the cause of pressure fall but without success. The release of LPG occurred for more than 5-10 minute The gas cloud grew to cover a large area and ignited from a ignition by ground flare. The VCE severely damaged the tank farm and resulted in LPG leak from other damaged tanks Just 4 minutes later first tank underwent BLEVE.

Over the next hour, 12 separate BLEVE explosions were recorded. The two largest BLEVE’s(from 2400 m3 spherical tanks) registered 5.0 seismic reading on R.S The explosions destroyed the local town of San Juan Ixhuatepec. Approximately 500-600 people killed and 5000-7000 others suffering severe burns.

11-Oct-12 Slide No.-6

Lessons Learned - San Juanico Disaster

Sitting of Major Hazard Installation • The high death toll occurred because the housing was too near to the plant. At the time the plant was constructed the area was underdeveloped, but over the years the built-up area had gradually crept up to the site.

Layout and Protection of large LPG Storages • The total destruction of the facility occurred because there was a failure of the overall system of protection, which includes layout, emergency isolation and water spray systems.

Gas Detection and Emergency Isolation • One feature which might have averted the disaster is more effective gas detection and emergency isolation. The plant had no gas detector system and probably as a consequence, emergency isolation was too late.

11-Oct-12 Slide No.-7

Mounded LPG Storage

A storage vessel sited above ground and completely covered by a mound of earth or similar inert material except for nozzles, manhole covers

Mounded Storage of LPG has proved to be safer compared to above ground storage

Eliminates the possibility of fire engulfment and radiation from a fire in close proximity.

11-Oct-12 Slide No.-8

Mounded LPG Storage

Mounded bullets have a sand cover around that can take impact of external projectiles/ flying object

Area of Land required to locate mounded bullet is minimal compared to conventional storage

Mounded storage is designed considering maximum working temperature as 55 deg C

11-Oct-12 Slide No.-9

Mounded Storage

11-Oct-12 Slide No.-10

Mound - Fabrication Mounded vessel(s) shall be placed on a firm foundation & installed so as to prevent movement or floatation.

The preferred type of foundation is a continuous sand bed, supporting the vessel over its full length.

The foundation shall be constructed with a slope of at least 1:200 to facilitate draining of the vessel.

The sand beneath the vessel shall be adequate elevation not less that 0.76 m to facilitate drainage.

Mound shall be earth, sand or non-combustible (vermiculate or perlite) for atleast 700 mm thickness.

The mound shall protect the vessel from radiation and robust against jet fire impingement.

The surrounding of bottom nozzle should be filled with such material that can absorb settlement.

Provision for monitoring settlement of the vessel at minimum 3 reference points shall be provided. 11-Oct-12 Slide No.-11

Mounded Storage Construction Methodology

11-Oct-12 Slide No.-12

Mounded Bullet

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Mounded Bullet

11-Oct-12 Slide No.-14

Engineers India Limited

Design ,Operation, maintenance of LPG Mounded Bullet 26th September 2012 11-Oct-12 Slide No.-15

Inherent Safety Aspects  Cover

of Mounded Bullet protects the vessel from Fire engulfment and radiation from a fire in close proximity  Intrinsically passive and safe environment eliminates possibility of Boiling Liquid Expanding vapour cloud explosion(BLEVE)  No “Domino Effect”  Reduced Fire case PSV loads as compared to Spheres  Reduced firewater requirement for fire fighting.  Difficult for external agencies to identify the mound as a storage facility

11-Oct-12 Slide No.-16

Facility Sitting/ Layout Considerations S.No

Description

Separation Distances* (m)

1

Between mounded storage and boundary, property line, group of buildings not associated with LPG Plant.

15

2

Between mounded storage and any other (other than pump/ compressor) facility associated with LPG plant.

15

3

Between mounded storage and fire water pump house and/ or fire water tank

30

Road of minimum 3.5 m width shall be provided around the mound for movement of earth moving/ fire fighting equipment

Accessibility to Fire tender at least two sides. Location of Fire hydrants and monitors at Safe distance. Locate LPG storage far away from Main Units in downwind direction Bullet dished ends not to face vital installation 2 m of Minimum inter-distance between the edge of the vessel(s) in a mound is maintained for bullets having diameter 2m and above to facilitate safe installation, testing, maintenance and removal of vessels. * Reference from OISD-150 11-Oct-12 Slide No.-17

Storage Principles  

   

  

LPG is commercial Butane and commercial Propane. LPG may be liquefied by moderately increasing the pressure or reducing temperature Refrigerated storage is used by suppliers to store large volume of LPG The main form of LPG storage is LPG Bullets Normally 85% of capacity is filled with liquid and the remaining space being taken up with vapor. As LPG is drawn from the Bullet ,vapor pressure in the Bullet drops and eventually the liquid boils and producing more vapor and restoring the pressure. When liquid temperature rises for instance in summer the vapor pressure increases . When liquid temperature drops, the vapor pressure drops. Typical Bullet size3500m3 of size 8000 MM ID X 80,000 MM (T/T) 11-Oct-12 Slide No.-18

Design Codes Standards

• • • • • • •

OISD-STD-150 (Design and Safety Requirements For LPG Mounded Storage Facility OISD-STD-144 (LPG Installations) OISD-STD-169 (Guidelines for small LPG Plants) OISD-STD-116 (Fire Protection facilities for Petroleum Refineries and Oil/Gas Processing) OISD-STD-118 (Layouts for Oil and Gas Installations) OISD-STD-152 (Safety instrumentation for process system in HC industry) OISD-STD-164 (Fire Proofing in Oil & Gas Industry)

• PD:5500, Specification of Unfired Fusion Welded Pressure Vessels, 2009 Edition • The Static and Mobile Pressure Vessels (Unfired) Rules, 1981, (with latest amendments)

Approval Given by Chief Controller of Explosives (CCOE ) as per SMPV Rules

11-Oct-12 Slide No.-19

Design Parameters Description

Values*

Design Code

ASME SEC VIII or PD – 5500 or equivalent duly approved by CCE

MOC (no H2S)

ASTM A 516 Gr. 70 (IT) or SA 537 C II (IT) or PD : 5500 or equiv

MOC (with H2S)

ASTM A 516 Gr. 60 or Equiv

Design Temperature

-27 °C to + 55 °C

Design Pressure

14.5 kg/cm2.g at top of the vessel

Corrosion Allowance

Minimum 1.5 mm (Internal)

Corrosion Protection

Cathodic Protection System Provided External surface of vessel are surface coated for protection from corrosion

Radiography

Full

Stress Relieving

100% irrespective of thickness

* Reference from OISD-150 11-Oct-12 Slide No.-20

Fittings and Instrumentation on Vessel Emergency Isolation • Fire Safe ROV shall be provided on first flange on liquid line (s), vapour outlet and re-circulation lines from the vessel either from bottom or. No other flanges is provided up to ROVs. • In case of liquid line from the bottom of the vessel, the minimum distance of 3 m from the vessel to ROV is maintained • The ROV is provided with volume bottle arrangement for two operation of ROV during instrumentation air failure

Safety Relief Valves • Each vessel shall be provided with at-least two safety relief valves whose capacity shall be minimum 30% of the capacity required for an equivalent size of above ground vessel. • All vents and drains are routed to closed Flare system where Flare is available. Otherwise vented vertically upwards to atmosphere ensuring effective dispersion of hydrocarbons

Level Indication • Minimum two different types of level indicators and one independent high level switch shall be provided. One transmitter shall be of Servo type and other Radar type. • Radar type level instrument shall have facility to measure RVP and temperature. • Min two number of manholes on the top of vessel is provided

Pressure and Temperature Indication • One pressure and temperature measuring instrument shall be provided. • PG shall be provided with two isolation valves and an excess flow check valve. 11-Oct-12 Slide No.-21

Mounded Lpg Storage 

11-Oct-12 Slide No.-22

Bottom Oulet Nozzle 

11-Oct-12 Slide No.-23

LPG - Water Drain System

Problem of ice formation preventing valve closure.

ANTIFREEZE GLOBE VALVE provided.

DEAD MAN HANDLE VALVE provided in series to ensure operator presence during the entire draining operation.

11-Oct-12 Slide No.-24

Gas Detection System

11-Oct-12 Slide No.-25

Fire Detection System Fire Detectors • Automatic fire detectors based on heat detection through thermal fuses/ quartz bulbs/ EP detectors shall be used

Sensor Location • Minimum one detector on each exposed portion of vessel. If nozzles are covered in dome, each group shall have at least two detectors. • At least one detector near ROV on all liquid line.

General Scheme for Quartzoid Bulb Detection

11-Oct-12 Slide No.-26

Actions on Fire Detection Audiovisual alarm at the local/ main control panel and fire water station, indicating the fire

All ROVs on the affected vessel shall close

LPG Pumps and Compressors in LPG Storage area shall trip.

Sprinklers if provided shall operate

11-Oct-12 Slide No.-27

Fire Water System & Fire Proofing Active Fire Protection  Hydrants and monitors are considered for adequate coverage of unprotected portions exposed to thermal radiation including the top of the mound and product pipelines  Hydrants and monitors are located at a safe place and shall not be installed within 15 meters from the exposed portion facilities/equipment  Auto actuated WaterSprinkler arrangement for top exposed domes, structures and pumps Passive Fire Protection  The fire proofing ( 2 Hours rating) of all exposed portion of the vessel is done including piping up to the first ROVs, appurtenances etc

11-Oct-12 Slide No.-28

Mounded Bullet

11-Oct-12 Slide No.-29

Mounded Bullet

11-Oct-12 Slide No.-30

Operation, Maintenance and Inspection Vessel shall be hydro-tested once every 10 years or at every welding whichever is earlier.

Vessel shall be tested every 5 years internally using visual and NDT Testing. Wall thickness shall be measured ultrasonically.

Safety relief valves shall be tested and calibrated every year.

Settlement of the vessel shall be monitored at least on half yearly basis.

Sprinkler spray density, flow rate and response time for every facility shall be verified once in every 6 months Cathodic protection System • CP system given for the bullet is to provide protection against soil side corrosion. • Protective potential readings to be monitored at fortnightly and quarterly intervals. • Insulating joints shall be inspected once in a year.

11-Oct-12 Slide No.-31

Operation, Maintenance and Inspection Maintenance & Testing stipulation given in the code aims to ensure integrity for continued operation.

LPG Vessels are known to suffer deterioration and failures.

Tests at 5 years intervals are extremely critical as the vessel is taken out of service and offers rare opportunity to inspect it from inside. Operators must engage specialist over and above NDT agency to get full benefit.

Other special NDT tests to be carried out are • Magnetic Particle Inspection • Ultrasonic Flaw Detection • Dye Penetrant Test • Hardness Measurement 11-Oct-12 Slide No.-32

Operation, Maintenance and Inspection It has been experienced that mounded bullets have suffered deterioration which was revealed during internal inspection.

In one such instance the defect was serious enough to call for derating of the vessel.

EIL’s specialist group was approached by the owner to avoid derating.

After thorough study, a rectification scheme was given which met the statutory approval and the bullet was brought back to sound health for normal operation.

11-Oct-12 Slide No.-33

Operation

11-Oct-12 Slide No.-34

Commissioning Commissioning of bullets are carried out as per following steps:  Cleaning and flushing /blowing of system  Tightness test with water/air/Nitrogen with maximum possible pressure app 10-12 kg/cm2 g  Simulated check of all controls and interlock  Check of all Security System

11-Oct-12 Slide No.-35

Commissioning       

Inertise with Nitrogen or completely fill up with water to displace air. In case of water, displace slowly water with LPG vapors by slowly draining water When pressure in bullet is equivalent to vapor pressure , pump in liquid LPG In case of Nitrogen , Nitrogen is to be purged with LPG vapor and also vent out to remove residual Nitrogen When pressure in bullet is equivalent to vapor pressure , pump in liquid LPG

11-Oct-12 Slide No.-36

Operation  Receiving

LPG product from Unit  Unloading LPG and receiving in bullet for initial requirement  Loading of LPG to Railway wagon  Loading of LPG to Road tanker  Transfer of LPG to Pipelines to Pump to other storage  Pump out of LPG received off-spec for reprocessing  Unloading of sick wagon or sick Tanker  Pump out for LPG vaporizer for Refinery scenario

11-Oct-12 Slide No.-37

Operation - Receiving Receiving

LPG product from Unit Normally all the vapor lines of Bullets are kept open Outlet and recirculation line valves are closed Inlet valve is opened and receiving line is lined up in the inlet manifold.

11-Oct-12 Slide No.-38

Operation-pump Out Pump

out for Reprocessing/Pump out for vaporizer/Transfer of LPG to Pipelines to Pump to other storage Outlet valve of Bullet is opened and lined up to Reprocessing Pump /Sale Pump/Vaporizer Feed Pump Inlet valve of Bullet is opened and MCF line is lined up to the Inlet manifold Pump is started with MCF lined up

11-Oct-12 Slide No.-39

Operation - Loading Loading

of LPG to Railway wagon/Loading of LPG to Road tanker Outlet valve of Bullet is opened and lined up to Loading Pump Recirculation line valves are opened and lined up to the same bullet Vapor space of the Wagon tanker /Road tanker is line up to vapor line to displace vapor while loading Pump is started with MCF lined up

11-Oct-12 Slide No.-40

Operation –Unloading Sick Tanker Unloading LPG and receiving in bullet for initial requirement/Unloading of sick tanker  Vapor line valve of Bullets are kept open an  Inlet opened and liquid line from tanker line is lined up to Inlet Header  Unloading compressor shall take vapor from vapor line and compress and route to tankers .  Tanker liquid is displaced with vapor  Liquid is routed to Bullet through Recirculation line  After complete unloading of liquid compressor is used to draw residual vapor from tanker and route to vapor phase of bullet through vapor line

11-Oct-12 Slide No.-41

Operation –Unloading Sick Tanker

11-Oct-12 Slide No.-42

THANK YOU

11-Oct-12 Slide No.-43