What is the Advantage and Disadvantage of API 6A Wellhead Systems

The American Petroleum Institute (or API) is an oil and gas industry trade association that oversees standards in oil and gas production. For example, API 6A defines the industry standards for wellhead and Christmas tree equipment and API 6D defines the industry standards for pipeline valves. Most people within the oil and gas industry have seen the phrase "API 6A valve" and "API 6D valve," but many may be unaware of what the API standards cover. Here are five facts about the API standards:API Standards are Used InternationallyThe International Organization for Standardization (or ISO) issues technical standards throughout the world. In the case of oil and gas production, the ISO has adopted the standards set by the API. For example, API 6A was adopted as ISO and API 6D was adopted as ISO . Thus, hydraulic gate valves used in Saudi Arabia and the United States, the world’s leading oil producers each having 13% of the world's total oil production, will meet exactly the same technical standards.API Standards Cover Specifications and Design of ValvesAPI standards cover everything about the design of a hydraulic gate valve, including the definition of "gate valve" as a "valve assembly with a gate operating within the body, 90 degrees to the conduit, to effect a closure." API 6A also covers the dimensions for a hydraulic gate valve, as well as the design of the threads, seats, and even the valve handwheel. For example, API 6A states that the handwheel must have spokes and must be replaceable while in service.API Standards Cover the Manufacture of ValvesIn addition to the design specifications, API standards also set specifications for the manufacture of hydraulic gate valves down to the hardness of the material used to make the valve and the chemical composition and dimensions of the welds. API 6A, for example, even specifies that welds must be made by qualified welders and records of the welders' performance qualification tests must be kept.API Standards Cover the Quality Control, Testing, and Marking of ValvesAPI 6A also establishes standards for quality control to ensure that the manufacturing standards are met. These quality control standards specify the manner for measuring and testing products made in accordance with API 6A. Specifically, API 6A defines standards for the testing equipment, quality control personnel, and testing procedures. API 6A also specifies when and how repair welds and re-manufactured pieces can be incorporated into products covered by the standard. Aside from visual examination, API 6A also specifies when and how harness tests, tensile tests, impact tests, chemical analysis, visual inspection, and non-destructive tests, such as ultrasonic and radiographic tests, are conducted. For certain uses, such as natural gas production, pressure tests using nitrogen or other inert gasses may be conducted. The standards specify how records of the testing are maintained and how the products are marked to indicate both compliance with the standards and how the testing records may be traced for those products.API Standards Vary Based on the ApplicationThe API standards are not "one size fits all." In fact, API 6A specifies five product specification levels (or PSLs) for different applications. To assist the end user in selecting the PSL for the user's application, API 6A includes a flowchart in figure A.3 of annex A of the standard. Matching the right PSL to the right use is very important. For example, PSL 3G is specified for parts used in natural gas production and, as such, requires gas testing of parts, whereas other PSLs are not directed for natural gas production and, as such, usually do not require gas testing.API 6A was written to ensure that oil and gas equipment is safe, reliable, and standardized. API standards cover everything from the design, materials, manufacture, testing, and marking of parts. In this manner, the end user can be assured that an API 6A hydraulic gate valve meets or exceeds the standards for quality and safety.

• 2-piece housing
• Type AST with trunnion mounted ball ≥ 2 1/16”
• Type ASF with floating ball for 10,000psi ≤ 2 1/16”
• Metallic sealing system with tungsten carbide hard-faced coating
• Triple shaft seals (type AST)
• Fugitive emission acc. ISO -1 up to +200°C
• Anti-blowout shaft /anti-static design
• Conforms DIN/ISO standard gear mounting
• Position indicator for open position on all ball valves ≥4 1/16”
• Drain port NPT or ISO incl. bleeder plug
• DIB-2 design* (type AST)

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*Double Isolation and Bleed 2 (DIB-2) design: has upstream seat equipped with a standard seat ring to
ensure pressure relief of valve cavity in the direction of the well. The downstream seat ring is equipped with
split seat ring to provide a “Double Piston effect” and seals in both directions. –› Double barrier against
well pressure.

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