What Is API 600?
API 600 is an American Petroleum Institute standard that specifies design, materials, dimensions, pressure-temperature ratings, inspection, and testing requirements for bolted-bonnet steel gate valves used in petroleum refining, petrochemical processing, and related industries. It ensures structural integrity, sealing reliability, and manufacturing consistency for large-diameter, high-pressure steel gate valves in process plant service — the complement to API 6D’s pipeline valve scope, and a foundational reference within the valve standards overview hub.
Key Takeaways
- API 600 applies to bolted-bonnet steel gate valves — the bolted bonnet configuration is the defining structural characteristic, distinguishing API 600 valves from pressure-seal bonnet designs used at the highest pressure classes and from compact gate valves covered by API 602.
- Primarily used in refinery and petrochemical service — crude distillation units, hydroprocessing reactors, catalytic cracking units, and high-temperature hydrocarbon process lines are the primary service environments for which API 600 design requirements are calibrated.
- Defines design, material, pressure rating, and testing requirements — wall thickness calculations per allowable stress limits, trim classification by hardness and corrosion resistance, body-bonnet gasket design, and hydrostatic shell and seat testing acceptance criteria are all defined within the standard.
- Ensures reliability in high-temperature and high-pressure environments — API 600 gate valves are designed for service from Class 150 through Class 2500 at temperatures from cryogenic to 816°C (1500°F) depending on material group, covering the full range of refinery process conditions from ambient atmospheric distillation to high-pressure high-temperature hydroprocessing.
How It Works
Scope and Refinery Application
API 600 defines its scope as steel bolted bonnet gate valves for petroleum and natural gas industries in NPS 1/2 through NPS 24 at Class 150 through Class 2500, with flanged, threaded, and butt-welding end connections. The bolted bonnet design — where the bonnet is secured to the body by a ring of bolts through a bonnet flange — is accessible for maintenance without removing the valve from the line: the bonnet can be unbolted and lifted to expose the stem, packing, wedge, and seats for inspection and replacement with the valve body remaining in the pipeline. This in-place maintainability is the primary structural advantage of bolted bonnet construction over pressure-seal designs for process plant service where maintenance access is available and frequent stem packing and seat replacement is anticipated over the valve’s 20-to-30-year service life. The refinery application context defines API 600’s design philosophy: gate valves in refinery service are typically operated infrequently — opened fully for normal flow and closed for maintenance isolation — and must maintain reliable sealing after extended periods of thermal cycling between ambient and operating temperature. API 600 does not address pipeline service, piggability, or double block and bleed capability — these requirements are addressed by API 6D. The broader valve standards framework that contextualizes API 600 within the full landscape of design, dimensional, testing, and certification standards is addressed in the valve standards overview reference.
Pressure-Temperature and Testing Requirements
API 600 references ASME B16.34 for all pressure-temperature ratings — the allowable working pressure at any operating temperature for an API 600 gate valve is determined from the ASME B16.34 pressure-temperature table for the valve’s body material group and ASME pressure class designation. For example, an API 600 Class 600 gate valve in ASTM A216 Grade WCB carbon steel is rated at 98.6 bar (1,430 psi) at 38°C, with the allowable pressure decreasing as temperature increases per the ASME B16.34 table — to 69.2 bar at 343°C and further as temperature approaches the material’s creep range above 425°C. The complete ASME B16.34 pressure-temperature rating framework and pressure class explanation are addressed in the what is ASME B16.34 and ASME pressure class explained references respectively. API 600 mandates production testing for every valve before shipment — shell hydrostatic test at 1.5 times the pressure-temperature rated pressure at room temperature (acceptance criterion: no visible leakage through body walls, bonnet joint, or gland area); seat leakage test at 1.1 times rated pressure (acceptance criterion per API 598 leakage class); and backseat test at 1.1 times rated pressure to verify that the backseat provides effective stem sealing when the gate is fully open. The complete API 598 testing framework applicable to API 600 valve production testing is addressed in the what is API 598 reference, with detailed testing procedures addressed in the valve pressure testing procedure reference.
Main Components
Body, Bonnet, and Wedge Construction
The valve body is the primary pressure-containing component, and API 600 specifies minimum wall thickness at all critical sections using the allowable stress method per ASME B16.34 Section 6 — the wall thickness must satisfy the pressure design equation at the design temperature using the material’s ASME Code allowable stress, with an additional corrosion allowance where specified by the purchaser. API 600 body castings must meet ASTM A216 Grade WCB (carbon steel), A217 Grade WC6 or WC9 (chrome-moly alloy steel for elevated temperature service), or A351 Grade CF8M (316 stainless steel for corrosive service) — the material group selection determines both the pressure-temperature rating and the compatibility with the process fluid’s corrosion conditions. The bonnet-to-body joint uses a spiral wound gasket or ring-type joint gasket seated in a raised-face or ring-joint flange configuration, with high-strength ASTM A193 Grade B7 stud bolts providing the joint load required to maintain gasket seating stress at maximum operating pressure and temperature. The wedge gate is the closure element — API 600 permits solid wedge, flexible wedge, and split wedge designs. The solid wedge is the simplest and most robust design, suitable for most services. The flexible wedge has relief machined around the perimeter to allow the gate face to deflect slightly to conform to the body seat faces under thermal distortion — preventing the gate from sticking in the closed position (thermal binding) after the valve is closed hot and the system cools, a failure mode that the solid wedge is susceptible to in high-temperature steam and process service. The complete gate valve design principles underlying the API 600 specification are addressed in the what is a gate valve reference.
Material and Certification Requirements
Material selection and traceability documentation are integral to API 600 compliance. All pressure-containing parts — body, bonnet, wedge, and bolting — must be made from materials meeting the chemical composition and mechanical property requirements of the applicable ASTM specification, with mandatory material identification marking linking each component to its material test certificate. API 600 requires EN 10204 Type 3.1 inspection certificates for pressure-containing parts as the standard material documentation requirement — these certificates show the actual chemical analysis and mechanical test results (yield strength, tensile strength, elongation, and Charpy impact energy at the applicable test temperature) for the specific heat of material used. The complete EN 10204 material certificate framework is addressed in the what is EN 10204 3.1 reference. The complete documentation package for a compliant API 600 valve delivery — including material certificates, dimensional inspection records, pressure test certificates, non-destructive examination records, and conformity declarations — is addressed in the valve certification documents reference. Verification that a delivered valve’s documentation package satisfies API 600 requirements is addressed in the how to verify valve compliance reference.
Fire and Emission Considerations
API 600 defines the core design and construction requirements for bolted bonnet gate valves but does not in itself mandate fire-safe or fugitive emission certification — these are supplementary requirements invoked by project specifications depending on the service environment and regulatory context. In hydrocarbon refinery service, gate valves at defined positions in flammable fluid service are typically required by project specification to carry fire-safe certification per what is API 607, demonstrating that the valve retains acceptable sealing integrity after exposure to fire conditions. The complete fire-safe certification qualification process is addressed in the fire-safe certification reference. In environmentally regulated refinery and chemical plant projects, gate valve stem seals are required to meet fugitive emission performance limits per ISO 15848 — classification A, B, or C tightness level with AH, BH, or CH thermal class designation. The complete fugitive emission testing framework applicable to API 600 gate valves is addressed in the fugitive emission testing and what is ISO 15848 references.
Advantages
Refinery Reliability and Global Acceptance
API 600’s combination of detailed design requirements, mandatory production testing, and comprehensive material traceability documentation provides a technically rigorous quality assurance framework that is trusted by refinery operators and engineering contractors globally. The standard’s long history — first published in 1962 and continuously revised through the current edition — means that the API 600 design requirements have been validated through decades of field service in refinery environments that subject gate valves to frequent thermal cycling, erosive fluid service, and the operational stresses of large-diameter high-pressure systems. The mandatory shell hydrostatic test at 1.5 times rated pressure and seat leakage test at 1.1 times rated pressure provide documented, quantitative verification of each individual valve’s pressure integrity before shipment — not statistical sampling of production lots. API 600 is recognized and specified globally in refinery and petrochemical project specifications, providing manufacturers with a single qualification framework that satisfies purchaser requirements without project-specific deviations. For the distinction between API 600 refinery gate valve requirements and API 6D pipeline valve requirements — which determines which standard governs at the boundary between refinery plant and pipeline service — refer to the what is API 6D and API 6D vs API 600 references.
Typical Applications
Refining, Petrochemical, and Power Systems
API 600 gate valves are the standard specification for steel isolation valves in petroleum refining process units across all operating sections from atmospheric distillation at Class 150 through hydroprocessing reactors at Class 900 and 1500. In crude distillation service, large-diameter Class 150 and Class 300 API 600 gate valves in ASTM A216 WCB carbon steel provide block valve isolation on atmospheric and vacuum distillation column inlet and outlet lines at temperatures to 370°C. In hydrotreating and hydrocracking reactor service, Class 600 through Class 1500 API 600 gate valves in ASTM A217 WC9 or F22 alloy steel resist hydrogen embrittlement and high-temperature sulfidation in high-pressure hydrogen-rich service per NACE RP0472 and API RP 942. In power generation steam systems, Class 900 through Class 2500 API 600 gate valves with pressure-seal bonnets — which supplement the standard bolted bonnet design at the highest pressure classes — provide main steam isolation in supercritical steam systems at pressures above 250 bar and temperatures above 565°C. In European refinery and petrochemical projects where both API 600 technical compliance and CE marking are required, the integration of API 600 with the Pressure Equipment Directive 2014/68/EU conformity assessment requirements is addressed in the what is PED 2014/68/EU reference.
Frequently Asked Questions
What type of valve does API 600 cover?
API 600 covers bolted-bonnet steel gate valves in NPS 1/2 through NPS 24 at Class 150 through Class 2500, with flanged, threaded, and butt-welding end connections, for service in petroleum refining, petrochemical processing, and related industries. It covers solid wedge, flexible wedge, and split wedge gate designs in carbon steel, alloy steel, and stainless steel body materials. It does not cover compact gate valves (covered by API 602), pressure-seal bonnet gate valves at the highest pressure classes (covered by ASME B16.34 directly), or pipeline gate valves (covered by API 6D).
How does API 600 differ from API 6D?
API 600 applies to bolted-bonnet steel gate valves for refinery and process plant service — where in-place bolted bonnet maintainability, wedge gate sealing integrity through thermal cycling, and compatibility with refinery piping systems are the governing design requirements. API 6D applies to pipeline valves — ball, gate, plug, and check valves for long-distance transmission service — where full-bore piggability, double block and bleed capability, and anti-static and fire-safe mandatory features address pipeline service requirements. An API 600 gate valve is a wedge gate design not required to be full bore; an API 6D gate valve is a through-conduit design maintaining full bore when open for pig passage.
Does API 600 define testing requirements?
Yes — API 600 mandates shell hydrostatic testing at 1.5 times the pressure-temperature rated pressure for every valve before shipment, with no visible leakage acceptance criterion for body, bonnet joint, and gland. Seat leakage testing at 1.1 times rated pressure is required with acceptance criteria per API 598 leakage class. Backseat testing at 1.1 times rated pressure is required to verify that the fully-open backseat position effectively seals the stem for repacking under pressure. All test results must be documented in a test certificate delivered with the valve.
Are API 600 valves required to be fire-safe?
API 600 itself does not mandate fire-safe certification — it is a design and construction standard for bolted bonnet gate valves and does not include fire test requirements. Fire-safe certification per API 607 may be required by project specifications for API 600 gate valves at valve positions in flammable hydrocarbon service where fire survivability is a safety requirement. When fire-safe certification is required, the purchaser must specify API 607 testing in the valve purchase specification as a supplementary requirement to the base API 600 compliance.
Conclusion
API 600 is the governing technical standard for steel bolted-bonnet gate valves in petroleum refining and petrochemical process service — its comprehensive requirements for bolted bonnet design, flexible wedge construction, ASME B16.34 pressure-temperature ratings, mandatory shell and seat production testing, full material traceability, and compatibility with supplementary fire-safe and fugitive emission certification requirements provide a complete quality assurance framework for the steel isolation gate valve category. Correct application requires confirming the valve’s nominal size, pressure class, body material group, and required supplementary certifications against the applicable project specification and process design conditions, then verifying the delivered documentation package against API 600 and supplementary standard requirements. Engineers requiring a comprehensive framework that integrates API 600 within the full landscape of valve design, testing, dimensional, and certification standards should consult the valve standards overview hub as the governing reference for all gate valve standards navigation.