API 6A.pdf

Muhammad Shafiq Mat Shayuti

X-mas trees: Control & regulate flow Wellheads: Support casing

Chrismast Tree - Well head, Single Composite Tree

• A Christmas Tree is an assembly of valves, spools, and fittings used for an oil well, gas well, water injection well, water disposal well, gas injection well, condensate well, and other types of wells. It is named for its resemblance to a decorate tree at Christmas. • Many times, the words Christmas Tree and Wellhead are used interchangeably; however, a wellhead and christmas tree are entirely separate pieces of equipment. • A wellhead must be present in order to utilize a Christmas tree and is used without a Christmas tree during drilling operations. Producing surface wells that require pumps (pump jacks, nodding donkeys, etc.) frequently do not utilize any tree due to no pressure containment requirement.

• Tree complexity has increased over the last few decades. They are frequently manufactured from blocks of steel containing multiple valves rather than made from multiple flanged valves. • The primary function of a tree is to control the flow into or out of the well, usually oil or gas. • A tree often provides numerous additional functions including chemical injection points, well intervention means, pressure relief means (such as annulus vent), tree and well monitoring points (such as pressure, temperature, corrosion, erosion, sand detection, flow rate, flow composition, valve and choke position feedback, connection points for devices such as down hole pressure and temperature transducer (DHPT).

• On producing wells, injection of chemicals or alcohols or oil distillates to prevent and or solve production problems (such as blockages) may be used. • A tree may also be used to control the injection of gas or water injection application on a producing or non-producing well in order to sustain economic "production" volumes of gas from other well(s) in the area (field). • •The control system attached to the tree controls the downhole safety valve (scssv, dhsv, sssv) while the tree acts as an attachment and conduit means of the control system to the down hole safety valve.

• There are five valves namely the Kill Wing valve, the Swab valve, the production wing valve, the upper master valve and lower master valve. • When the operator, well, and facilities are ready to produce and receive oil or gas, valves are opened and the release of the formation fluids is allowed to flow into and through a pipeline. It is important to understand where these valves are located and what role they play in getting gas from the well bore to the customer.

• The two lower valves are called the master valves (upper and lower respectively) because they lie in the flow path, which well fluids must take to get to surface. • The lower master valve will normally be manually operated, while the upper master valve is often hydraulically actuated. • Hydraulic tree wing valves are usually built to be fail safe closed, meaning they require active hydraulic pressure to stay open.

• •The right hand valve is often called the flow wing valve or the production wing valve, because it is in the flow path the hydrocarbons take to production facilities. • •The left hand valve is often called the kill wing valve. It is primarily used for injection of fluids such as corrosion inhibitors or methanol to prevent hydrate formation. • •The valve at the top is called the swab valve and lies in the path used for well interventions likewireline and coiled tubing. • A ‘Choke’ is a device, either stationary or adjustable, used to: •control the gas flow, also known as volume •or create downstream pressure, also known as back pressure

Scope Repair & Remanufacture

Design & Performance

Equipment Spec. Requirement

Materials

Storing & Shipping

Welding

Equipment Marking

Quality Control

• Equivalent to ISO 10423 • This International Standard specifies requirements and gives recommendations for the performance, dimensional and functional interchangeability, design, materials, testing, inspection, welding, marking, handling, storing, shipment, purchasing, repair and remanufacture of wellhead and christmas tree equipment for use in the petroleum and natural gas industries. • Applied for Wellhead equipment, Connectors and fittings, Casing and tubing hangers, Valves and chokes, Loose connectors [flanged, threaded, other end connectors (OEC), and welded, actuators, etc.

• This International Standard establishes requirements for five product specification levels. These five PSL designations define different levels of technical quality requirements. Annex A provides guidelines (not requirements) for selecting an acceptable PSL.

PSL

Description

PSL 1

includes practices currently being implemented by a broad spectrum of the industry for service conditions recommended in this Annex A.

PSL 2

includes all the requirements of PSL 1 plus additional practices currently being implemented by a broad spectrum of the industry for a specific range of service conditions as described in this Annex A.

PSL 3

includes all the requirements of PSL 2 plus additional practices currently being implemented by a broad spectrum of the industry for a specific range of service conditions as described in this Annex A.

PSL 3G

includes all the requirements of PSL 3 plus additional practices currently being implemented by a broad spectrum of the industry for a specific range of service conditions as described in this Annex A. The designation PSL 3G is only utilized in those clauses and tables where necessary to define the additional gas-testing requirements of equipment that can be gastested.

PSL 4

includes all the requirements of PSL 3G plus certain additional requirements and is intended for applications that exceed the service conditions usually identified within the scope of this International Standard, and is normally only used for primary equipment.

• Figure A.3 on the next slide shows the recommended specification level for primary equipment. Primary equipment of a wellhead assembly includes as a minimum: • • • •

tubing head; tubing hanger; tubing head adapter; lower master valve.

• All other wellhead parts are classified as secondary. The specification level for secondary equipment may be the same as or less than the level for primary equipment. • The selection of PSL should be based on a quantitative risk analysis which is a formal and systematic approach to identifying potentially hazardous events, and estimating the likelihood and consequences to people, environment and resources, of accidents developing from these events.

• Equipment shall be designed to operate at only the following maximum rated working pressures:

• Flanges specified in this International Standard are to be designed in accordance with design criteria and methods originally developed by API.

• Design of end and outlet hub connections (16B and 16BX) used on equipment specified in this International Standard shall conform to the material and dimensional requirements of ISO 13533.

• Clamps meeting the requirements of ISO 13533 are acceptable for installation on equipment specified in this International Standard with integral hubs meeting the requirements of ISO 13533.

• Casing hangers, tubing hangers, back-pressure valves, lock screws and stems shall be designed to satisfy the manufacturer's documented performance characteristics and service conditions as in 4.2. The manufacturer shall specify methods to be used in design which are consistent with accepted engineering practices.

• Other end connectors, bodies and bonnets that utilize standard materials (in designs other than those specified in this International Standard) shall be designed in accordance with one or more of the following methods. Standard materials are those materials whose properties meet or exceed the requirements of Table 5. • Other end connectors, bodies and bonnets that utilize nonstandard materials shall be designed in accordance with the requirements of 4.3.3.6. Non-standard materials are materials with specified minimum yield strength in excess of 517 MPa (75 000 psi) that do not meet the ductility requirements of Table 5 for standard 75K materials.

• In the event stress levels calculated by the methods in 4.3.3.2 to 4.3.3.6 exceed the allowable stresses, other methods identified by the manufacturer shall be used to justify these stresses. Fatigue analysis and localized bearing stress values are beyond the scope of this International Standard.

1. ASME method 2. Theory of constant energy of distortion 3. Experimental stress analysis (Experimental stress analysis as described in ASME, Section VIII, Division 2, Appendix 6 may be used as an alternative method to those described in 4.3.3.2 and 4.3.3.3.) 4. Design qualification by proof test (As an alternative to the analytical methods, the pressure rating of equipment may be determined by the use of a hydrostatic test at elevated pressure) 5. Non-standard materials design requirements

• This clause describes the material performance, processing and compositional requirements for bodies, bonnets, end and outlet connections, hub end connectors, hangers, back-pressure valves, bull plugs, valve-removal plugs, wear bushings, pressure-boundary penetrations and ring gaskets. Other pressure-containing and pressure controlling parts shall be made of materials that satisfy 5.2 and the design requirements of Clause 4. • All material requirements in this clause apply to carbon steels, lowalloy steels and martensitic stainless steels (other than precipitationhardening types). Other alloy systems (including precipitationhardening stainless steels) may be used provided they satisfy the requirements of this clause and the design requirements of Clause 4.

The manufacturer's written specified requirements for metallic materials for bodies, bonnets, end and outlet connections, stems, valve bore sealing mechanisms, back-pressure valves, bullplugs and valve-removal plugs and mandrel hangers shall define the following along with acceptlreject criteria: a) for PSL 1: I. II. III. IV. V. VI.

mechanical property requirements; material qualification; heat-treatment procedure including cycle time, quenching practice and temperatures with tolerances and cooling media; material composition with tolerances; NDE requirements.

b) for PSL 2 to PSL 4: I. II. III. IV.

The requirements for PSL 2 to PSL 4 are identical to the requirements for PSL 1. In addition: allowable melting practice(s); forming practice(s), including hot-working and cold-working practices; heat-treating equipment calibration.

Bodies, bonnets, end and outlet connections a) Tensile property requirements All bodies, bonnets, end and outlet connections shall be fabricated from standard or non-standard materials as specified in Table 4. Standard materials shall meet the applicable properties shown in Table 5. Non-standard material shall conform to the manufacturer's written specification. The specification shall include minimum requirements for tensile strength, yield strength, elongation, reduction of area, toughness and hardness applicable for the specific alloy. All non-standard materials shall exceed a 75K minimum yield strength and meet a minimum of 15 % elongation and 20 % reduction of area.

b) Impact toughness requirements Impact toughness shall conform to the requirements of Table 6. If sub-size specimens are used, the Charpy V-notch impact requirements shall be equal to that of the 10 mm x 10 mm specimens multiplied by the adjustment factor listed in Table 7. Sub-size specimens shall not be used for PSL 4.

• Requirements are established in four groups as follows: a) Non-pressure-containing weldments other than weld overlays: PSL 1 to PSL 3. b) Pressure-containing fabrication weldments for bodies, bonnets, and end and outlet connections, bullplugs, valve-removal plugs and back-pressure valves: PSL 1 to PSL 3. c) Pressure-containing repair weldments for bodies, bonnets, and end and outlet connections, bullplugs, valveremoval plugs and back-pressue valves: PSL 1 to PSL 3.

d) Weld overlay for corrosion resistance and/or hard facing and other material surface property controls: PSL 1 to PSL4.

• This clause specifies the quality control requirements and quality control record requirements for equipment and material manufactured to meet this International Standard.

• Equipment shall be marked on the exterior surface as specified in Table 27. Marking shall contain the designation ISO 10423, the temperature rating, material class, product specification level, performance requirement level, date of manufacture (month and year), and manufacturer's name or mark. Other marking shall be as specified in Tables 27, 28, 29, 30, 31, 32, 33 and 34. Marking for features that do not exist on a product is not applicable.

• Spells out requirements when storing and shipping, some dependent of PSL.

• As per the document.

• Requirements for repair and remanufacture are specified in Annex J.