API Specification 6A, 21st Edition

We are pleased to announce the publication of the 21st edition of Specification 6A, Wellhead and Tree Equipment. This new edition provides technical updates that have reached consensus within API’s Subcommittee on Valves & Wellhead Equipment and will now give industry consistent practices in these respective areas of the standard. These updates are reflective of API’s standards program mission to provide a forum for development of consensus-based industry standards, and technical cooperation to improve the industry’s safety performance and competitiveness.

If you want to learn more, please visit our website Yulin Machinery.

Key Changes:

Revision of the document will include:

• A complete reorganization of the document—quality requirements are now grouped by specific activity and not by PSL, making it easier to determine the specific requirements for all PSLs in one location and not spread throughout the document. 
• Uniformity in the layout of the product-specific section.
• A total revision of all of the sizing tables, including associated figures, to allow for clearer understanding of the requirements. The tables exist as a full set in SI (metric) units and as a separate, exact set in USC (imperial) units.
• Uniform use of product terms throughout the document.
• Revision of the annexes:
• Incorporation of annexes, in the body of the document (former Annex L and Annex O);
• Former Annex J will be published as a new document, 6AR; former Annex H will be published within TR6RT; and former Annex I will be deleted in lieu of fully referencing 6AV1;
• Former Annex E and Annex N were withdrawn as they are no longer needed/applicable to the document.
• Addition of a new product (proposed for monogramming), boarding shutdown valves, developed with support of the regulatory community. The casing and tubing hangers product line is better defined for slip and mandrel hangers, two separate products. So, in effect, there will be three new products.
• Removal of fluid sampling devices.
• Integration of tubing head adapter requirements into overall head requirements for a more integrated product.
• Required minimum PSL depending on the pressure rating and material class. Revised PSL 4 to target critical service equipment.
• Heat treatment requirements now normative.
• Removal of PR1 from design validation annex.
• Addition of pressure boundary qualification requirements.
• Creation of a new section on records and records control.
• Factory acceptance testing (FAT) removed from the quality section; section reorganized and requirements presented in a more logical order.
• Marking requirements now target specific products and not product families to better target specific marking needs.
• Required minimum 20E and 20F BSL for bolting.

Effective Date and Program Implications

The API Monogram Program effective date will be November 1, .

Current licensees shall ensure that products manufactured on and after November 1, meet the requirements of API 6A, 21st edition in order to be monogrammed.

Also, effective November 1, , API 6A audits will be conducted to the 21st edition of the document.

To Purchase

Specification 6A is available on API’s new Compass platform. A Compass subscription gives you organization-wide, 24/7 access to all of the API standards and specifications you need to ensure safety, compliance, and interoperability. With a subscription on Compass, you are ensured consistent and up-to-date access to the latest API standards.  For additional information, please use the  or visit API's Standards Subscription Service.

• The subscription updates itself, so your subscription automatically reflects the latest edition.
• 24/7 desktop access to critical information for all users at the licensed location.
• Version comparison to quickly identify critical changes.
• The ability to collaborate internally within the standard.

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Additional Information and Questions

The companion video, highlighting key changes and the implications for API Monogram licensees, will be available in early .

To receive direct notification of when registration is open, please   with the subject “6A”.

For more information, please visit API 6A Wellhead Systems.

API receives numerous inquiries related to its standards, specifications, recommended practices, technical reports, and codes (i.e. documents). While we can provide answers to many of these questions, there are certain categories of queries for which API cannot provide assistance. We use the terms “General and Technical Questions” and “Requests for Interpretation” to describe the typical categories of questions we receive. The information below will help you understand what type of questions we can answer and how to go about submitting your question to us for consideration.

Often Great Lakes Wellhead gets asked, “Which seal is best for my Wellhead?” Here is what we think!

The deciding factors for determining which seal should be used in your wellhead should be based on temperature, environmental conditions, and cost.

Temperature is the most common deciding factor for determining which seal is best to use. Factors to consider when determining temperature include atmospheric temperature, formation or fluid temperature and welding temperature (Preheat and Post weld heat). The following table shows the temperature ranges of various seal elastomers commonly used in API 6A wellheads.

Figure 1: Temperature Rating Chart for common elastomers used in seals

Environmental conditions will also determine which seat compound to use. For the oil and gas industry, factors to consider include: H2S, Chemical treatments, particulates (debris, sand, salt), the velocity of fluids, CO2, Ozone or Sunlight, Fungus or Mold, and oxidation. 

Common seals used in our industry are BUNA (NBR or Nitrile Rubber), VITON (Fluorocarbon, FKM or FPM), or HSN (Highly Saturated Nitrite or HNBR).

All provide excellent compression set resistance and both are designed to resist most oils and lubricants, especially petroleum-based lubricants.

BUNA (NBR or Nitrile Rubber)

• Temp range from -50 to 250 degrees F. Superior low temp capabilities compared to Viton but can only go to 250F.
• Very abrasion and tear-resistant.
• Resistant to oils and lubricants especially petroleum-based lubricants.
• Poor performance against chemicals, weather, and ozone. In most applications, weather and ozone is not an issue.
• Cheaper options compared to the other seals.

VITON (Fluorocarbon, FKM, or FPM)

• Temp range from 0 to 400F but can withstand short times slightly outside of that range.
• Resistant to oils and lubricants, a wide variety of chemicals and weather, and ozone.
• Less abrasion and tear-resistant than BUNA.
• More expensive

HSN (Highly Saturated Nitrite or HNBR)

• Temperature ranges from -40 to 310F.
• A process of hydrogenerating the nitrile copolymer provides excellent resistance to oils and lubricants, ATF, sour gas, amine/oil mixtures, oxidized fuels, and lubricating oils.
• Improved design from VITON and BUNA for harsher environments where H2S is prevalent.

All of these seals provide good to excellent resistance to the common chemicals used in the oil and natural gas industry. Some of the more exotic chemical treatments may present an issue and should be examined on a case-by-case basis. A good resource for reviewing the compatibility of specific chemicals can be found here: https://www.coleparmer.com/Chemical-Resistance

For more Flanges Manufacturerinformation, please contact us. We will provide professional answers.