of the American Petroleum Institute
API Std 520
Sizing, Selection, and Installation of Pressure-relieving Devices in Refineries, Part I - Sizing and Selection.
This standard applies to the sizing and selection of pressure relief devices used in refineries and related industries for equipment that has a maximum allowable working pressure of 15 psig (103 kPag) or greater.
The pressure relief devices covered in this standard are intended to protect unfired pressure vessels and related equipment against overpressure from operating and fire contingencies.
This standard includes basic definitions and information about the operational characteristics and applications of various pressure relief devices. It also includes sizing procedures and methods based on steady state flow of Newtonian fluids. Pressure relief devices protect a vessel against overpressure only; they do not protect against structural failure when the vessel is exposed to extremely high temperatures such as during a fire. See API 521 for information about appropriate ways of reducing pressure and restricting heat input.
Atmospheric and low-pressure storage tanks covered in API 2000 and pressure vessels used for the transportation of products in bulk or shipping containers are not within the scope of this standard.
The rules for overpressure protection of fired vessels are provided in ASME Section I and ASME B31.1, and are not within the scope of this standard.
API RP 520
Sizing, Selection, and Installation of Pressure-Relieving Devices in Refineries-Part II, Installation.
This standard covers methods of installation for pressure-relief devices for equipment that has a maximum allowable working pressure (MAWP) of 15 psig (1.03 bar g or 103 kPA) or greater. Pressure relief valves or rupture disks may be used independently or in combination with each other to provide the required protection against excessive pressure accumulation. The term pressure relief valve includes saferty relief valves used in either compressible or incompressible fluid service, and relief valves used in incompressible fluid service. It covers gas, vapor, steam, two-phase and incompressible fluid service; it does not cover special applications that require unusual installation considerations.
API Std 526
Flanged Steel Pressure-relief Valves.
This standard is a purchase specification for flanged steel pressure-relief valves. Basic requirements are given for direct spring-loaded pressure-relief valves and pilot-operated pressure-relief valves as follows:
- orifice designation and area
- valve size and pressure rating, inlet and outlet
- pressure-temperature limits
- center-to-face dimensions, inlet and outlet
Nameplate nomenclature and requirements for stamping are detailed in Annex A.
API Std 527
Seat Tightness of Pressure Relief Valves.
This standard describes methods of determining the seat tightness of metal- and soft-seated pressure relief valves, including those of conventional, bellows, and pilot-operated designs.
API RP 574
Inspection Practices for Piping System Components.
This recommended practice (RP) supplements API 570 by providing piping inspectors with information that can improve skill and increase basic knowledge and practices. This RP describes inspection practices for piping, tubing, valves (other than control valves), and fittings used in petroleum refineries and chemical plants. Common piping components, valve types, pipe joining methods, inspection planning processes, inspection intervals and techniques, and types of records are described to aid the inspector in fulfilling their role implementing API 570. This publication does not cover inspection of specialty items, including instrumentation and control valves.
API RP 576
Inspection of Pressure-relieving Devices.
API Recommended Practice 576 describes the inspection and repair practices for automatic pressure-relieving devices commonly used in the oil and petrochemical industries. As a guide to the inspection and repair of these devices in the user's plant, it is intended to ensure their proper performance. This publication covers such automatic devices as pressure-relief valves, pilot-operated pressure-relief valves, rupture disks, and weight-loaded pressure-vacuum vents.
The scope of this RP includes the inspection and repair of automatic pressure-relieving devices commonly used in the oil and petrochemical industry. This publication does not cover weak seams or sections in tanks, explosion doors, fusible plugs, control valves, and other devices that either depend on an external source of power for operation or are manually operated. Inspections and tests made at manufacturers' plants, which are usually covered by codes or purchase specifications, are not covered by this publication.
This publication does not cover training requirements for mechanics involved in the inspection and repair of pressure-relieving devices. Those seeking these requirements should see API 510, which gives the requirements for a quality control system and specifies that the repair organization maintain and document a training program ensuring that personnel are qualified.
API STD 594
Check Valves: Flanged, Lug, Wafer and Butt-welding.
This international standard covers design, material, face-to-face dimensions, pressure-temperature ratings, and examination, inspection, and test requirements for two types of check valves.
API Std 598
Valve Inspection and Testing.
API 598 covers inspection, examination, supplementary examinations, and pressure test requirements for resilient-seated, nonmetallic-seated (e.g. ceramic), and metal-to-metal-seated valves of the gate, globe, plug, ball, check, and butterfly types.
API Std 599
Metal Plug Valves-Flanged, Threaded and Welding Ends.
This standard covers design, materials, face-to-face dimensions, pressure-temperature ratings, and examination, inspection, and test requirements for metallic plug valves.
This standard includes requirements for valves fitted with internal body, plug, and port linings or applied hard facings on the body, body ports, plug, and plug port. The extent of linings and the facing materials of which they are made are not covered in this standard.
This standard also provides additional requirements for plug valves that are in full conformance to the requirements of ASME B16.34 for Standard Class 150 through 2500. Ductile iron valves, Class 150 and 300, shall follow the additional requirements of ASME B16.42 for pressure-temperature ratings, wall thickness, flange dimensions, and material grade.
Plug valves covered in this standard belong to one of four general design groups that in many cases have different face-to-face and end-to-end dimensions. Some types of plug valves are not made to all patterns. The four groups of valve design are described below.
The standard nomenclature for valve parts is shown in Annex B. Figure B.1, Figure B.2, Figure B.3, and Figure B.4 illustrate typical plug valve designs and are not to be construed as precluding other available designs that comply with the requirements of this standard. The only purpose of these figures is to identify part names. The construction of a valve is acceptable only when it complies with this standard in all respects.
API Std 600
Steel Gate Valves - Flanged and Butt-welding Ends, Bolted Bonnets.
This International standard specifies the requirements for a heavy-duty series of bolted bonnet steel gate valves for petroleum refinery and related applications where corrosion, erosion and other service conditions would indicate a need for full port openings, heavy wall sections and large stem diameters.
API Std 602
Steel Gate, Globe and Check Valves for Sizes DN 100 and Smaller for the Petroleum and Natural Gas Industries.
This international standard specifies the requirements for a series of compact steel gate, globe and check valves for petroleum and natural gas industry applications.
It is applicable to valves of:
- nominal pipe sizes NPS1/4, NPS 3/8, NPS 1/2, NPS 3/4, NPS 1, NPS 1¼, NPS 1½, NPS 2, NPS 2½, NPS 3, and NPS 4
- corresponding to nominal sizes DN 8, DN 10, DN 15, DN 20, DN 25, DN 32, DN 40, DN 50, DN 65, DN 80, and DN 100
It is also applicable to pressure designations of Class 150, Class 300, Class 600, Class 800 and Class 1500.
Class 800 is not a listed class designation, but is an intermediate class number widely used for socket welding and threaded end compact valves.
It includes provisions for the following valve characteristics.
- Outside screw with rising stems (OS & Y), in sizes1/4 < or = NPS < or = 4 (8 < or = DN < or = 100) and pressure designations including Class 800
- Inside screw with rising stems (ISRS), in sizes1/4 < or = NPS < or = 2½ (8 < or = DN < or = 65) and pressure designations of classes < or = 800
- Socket welding or threaded ends, in sizes1/4 < or = NPS < or = 2½ (8 < or = DN < or = 65) and pressure designations of Class 800 and Class 1500
- Flanged or butt-welding ends, in sizes 1/2 < or = NPS < or = 4 (15 < or = DN < or = 100) and pressure designations of Class 150 through Class 1500, excluding flanged end Class 800
- Bonnet Joint Construction-Bolted, welded and threaded with seal weld for classes < or = 1500 and union nut for classes < or = 800
- Standard and full-bore body seat openings
- Materials, as specified
- Testing and inspection
This publication is applicable to valve end flanges in accordance with ASME B16.5, valve body ends having tapered pipe threads to ASME B1.20.1 or ISO 7-1, valve body ends having socket weld ends to ASME B16.11 and butt-weld connections per the requirements described within this standard. It is applicable to extended body construction in sizes 1/2 < or = NPS < or = 2 (15 < or = DN < or = 50) and pressure designations of Class 800 and Class 1500, and to bellows and bellows assembly construction as may be adaptable to gate or globe valves in sizes1/4 < or = NPS < or = 2 (8 < or = DN < or = 50). It covers bellows stem seal type testing requirements.
API Std 603
Corrosion-resistant, Bolted Bonnet Gate Valves-Flanged and Butt-welding Ends.
This standard specifies the requirements for corrosion-resistant bolted bonnet gate valves meeting the requirements of Standard Class, ASME B16.34 and having full port openings for use in process piping applications. This standard sets forth the requirements for the following gate valve features:
- bolted bonnet
- outside screw and yoke
- rising stems
- non-rising handwheels
- single or double gate
- wedge or parallel sealing
- metallic seating surfaces
- flanged or butt-welding ends
Corresponding to nominal pipe size DN:
15, 20, 25, 32, 40, 50, 65, 80, 100, 150, 200, 250, 300, 350, 400, 450, 500, 600.
It covers valves of the nominal pipe size NPS:
1/2, 3/4, 1, 1¼, 1½, 2, 2½, 3, 4, 6, 8, 10, 12, 14, 16, 18, 20, 24.
Applies to pressure class designations: 150, 300, 600.
Annex B illustrates a bolted bonnet gate valve for the purpose of establishing standard nomenclature for valve parts.
API Std 607
Fire Test for Quarter-turn Valves and Valves Equipped with Nonmetallic Seats.
This International Standard specifies fire type-testing requirements and a fire type-test method for confirming the pressure-containing capability of a valve under pressure during and after the fire test. It does not cover the testing requirements for valve actuators other than manually operated gear boxes or similar mechanisms when these form part of the normal valve assembly. Other types of valve actuators (e.g. electrical, pneumatic, or hydraulic) may need special protection to operate in the environment considered in this valve test, and the fire testing of such actuators is outside the scope of this International Standard.
API Std 608
Metal Ball Valves-Flanged, Threaded and Welding Ends.
This standard specifies the requirements for metal ball valves suitable for petroleum, petrochemical, and industrial applications that have:
- flanged ends in sizes DN 15 through DN 600 (NPS 1/2 through NPS 24)
- butt welding ends in sizes DN 15 through DN 600 (NPS 1/2 through NPS 24)
- socket welding ends in sizes DN 8 through DN 50 (NPS1/4 through NPS 2)
- threaded ends in sizes DN 8 through DN 50 (NPS1/4 through NPS 2)
Corresponding to the nominal pipe sizes in ASME B36.10M.
This standard applies to metal ball valves with pressure classes as follows:
- flanged ends in Classes 150, 300, and 600
- butt welding ends in Classes 150, 300, and 600
- socket welding ends in Classes 150, 300, 600, and 800
- threaded ends in Classes 150, 300, 600, and 800
This standard establishes requirements for bore sizes described as:
- full bore
- single reduced bore
- double reduced bore
This standard applies to floating (seat-supported) ball (Figure B.1) and trunnion ball valve designs (Figure B.2). These figures are to be used only for the purpose of establishing standard nomenclature for valve components - other floating and trunnion designs also exist. This standard establishes additional requirements for ball valves that are otherwise in full conformance to the requirements of ASME B16.34, Standard Class.
API Std 609
Butterfly Valves: Double-flanged, Lug- and Wafer-type.
This standard covers design, materials, face-to-face dimensions, pressure-temperature ratings, and examination, inspection and test requirements for gray iron, ductile iron, bronze, steel, nickel-based alloy, or special alloy butterfly valves that provide tight shutoff in the closed position. The following two categories of butterfly valves are included.
Category A-Manufacturer's rated cold working pressure (CWP) butterfly valves, usually with a concentric disc and seat configuration. Sizes covered are NPS 2 to NPS 48 for valves having ASME Class 125 or Class 150 flange bolting patterns.
Category B-ASME Class and pressure-temperature rated butterfly valves that have an offset seat and either an eccentric or a concentric disc configuration. These valves may have a seat rating less than the body rating. For lug and wafer, Class 150, 300, and 600, sizes covered are NPS 3 to NPS 24. For double flanged long pattern, Class 150, 300, and 600, sizes covered are NPS 3 to NPS 36. For double flanged short pattern, Class 150 and 300, sizes covered are NPS 3 to NPS 48. For double-flanged short pattern, Class 600, sizes covered are NPS 3 to NPS 24.
API Spec 6D
Specification for Pipeline Valves.
API Specification 6D is the (proposed) national adoption of ISO 14313: 1999, Petroleum and Natural Gas Industries-Pipeline Transportation Systems-Pipeline Valves. This International Standard specifies requirements and gives recommendations for the design, manufacturing, testing and documentation of ball, check, gate and plug valves for application in pipeline systems.
API Spec 6FA
Fire Test for Valves.
It is the purpose of this document to establish the requirements for testing and evaluating the pressure-containing performance of API Specs 6A amd 6D valves when exposed to fire. The performance requirements of this document are intended to establish standard limits of acceptabliltyregardless of size or pressure rating.This document establishes acceptable levels for leakage through the test valve and also external leakage after exposure to a fire for a 30 minute time perioud. The burn period has been established on the basis that it represents the maximun time required to extinguish most fires. Fires of greater duration are considered to be of a major magnitude with consequences greater than those anticipated in this test. This standard covers the requirements for testing and evaluating the performance of API Specs 6A and 6D valves when exposed to specifically defined fire conditions. However, this standard is not intended to cover check valves or end connections.
API Spec 6FC
Specification for Fire Test for Valves with Automatic Backseats.
This document establishes the requirements for testing and evaluating the pressure-containing performance of API Specification 6A and API Specification 6D automatic backseating valves when exposed to fire. The performance requirements of this document are intended to establish standard limits of acceptability regardless of size or pressure rating.
This document establishes acceptable levels for leakage through the test valve and also external leakage after exposure to a fire for a 30-minute time period, both before and after reworking the stuffing box. The burn period has been established on the basis that it represents the maximum time required to extinguish most fires. Fires of greater duration are considered to be of a major magnitude with consequences greater than those anticipated in this test.
Referenced Standards for Committee 6, Standardization of Valves and Wellhead Equipment.
API RP 11V6
Design of Continuous Flow Gas Lift Installations Using Injection Pressure Operated Valves.
Intended to set guidelines for continuous flow gas lift installation designs using injection pressure operated valves. The assumption is made that the designer is familiar with and has available data on the various factors that affect a design.
API RP 11V7
Recommended Practice for Repair, Testing, and Setting Gas Lift Valves.
Applies to repair, testing, and setting gas lift valves and reverse flow (check) valves. It presents guidelines related to the repair and reuse of valves; these practices are intended to serve both repair shops and operators. The commonly used gas pressure-operated bellows valve is also covered. Other valves, including bellows charged valves in production pressure (fluid) service should be repaired according to these guidelines.