For API 17D.pdf

2.4 Ring Gasket Profile Designs (Types) Illustrated and Explained R TYPE

R TYPE

R TYPE

OVAL RING GASKET

OCTAGONAL RING GASKET

COMBINATION RING GASKET

RX TYPE

SRX TYPE

BX TYPE

SBX TYPE

PRESSURE PRESSURE PRESSURE PRESSURE ENERGIZED ENERGIZED ENERGIZED ENERGIZED SUBSEA RING SUBSEA RING RING GASKET RING GASKET GASKET GASKET

The illustrations show the various types of API ring gaskets in cross-section. Except for the offering of styles of R type ring gaskets, each gasket shown has a special intended purpose and in some cases a clear advantage in application. API does not specify pressure balancing holes in all RX ring gaskets as illustrated above. All RX ring gaskets without these holes may have modification to include pressure balancing holes. All RX and BX ring gaskets may also have vent holes to the equipment bores to facilitate subsea make-up of connections (see the profiles of SRX and SBX ring gaskets).

R TYPE OVAL RING GASKET

R TYPE OCTAGONAL RING GASKET

R TYPE COMBINATION RING GASKET

R type oval ring gaskets have the greatest application of all ring gaskets used in industry today. These gaskets fit API 6B and ASME B16.5 flanges. Oval type R gaskets fit all current specification ring grooves, as well as "round bottom" ring grooves found in some older flanges.

R type octagonal ring gaskets offer an alternative to the more common (for wellheads) R type oval ring gasket. These gaskets also fit API 6B and ASME B16.5 flanges. R type octagonal ring gaskets fit all current specification ring grooves, but operators must use care to avoid their use in "round bottom" ring grooves found in some older flanges.

R type combination ring gaskets have different designations on each side. Combination ring gaskets allow the connection of flanges, with the same bolt circle measurement and number of bolt holes, that have different designated gaskets. (Such connected flanges may or may not require specially dimensioned bolts).

RX type ring gaskets have a non-symmetrical octagonal cross-section. This non-symmetrical geometry provides an unbalanced contact with the flange ring groove resulting in coining and sealing on the O.D. of the gasket only. The RX type ring gasket geometry provides a pressure-energized self sealing effect. RX type ring gaskets increase the stand-off between flange faces and flange bolt length must accommodate this additional stand-off.

RX TYPE PRESSURE ENERGIZED RING GASKET www.woodcousa.com

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A Brief History of Flanges (To Identify API Wellhead Flanges, Click Here) (Jump down to: ASA Flanges, ANSI Flanges, API 6AB Flanges, MSS-SP-44 Flanges)

Today API Spec 6A and MSS SP-44 specify all flanges commonly used in surface drilling and production. These flanges have a long history and many flanges used in the past have been discontinued, or obsoleted and replaced by more modern configurations. Originally, all flanges related to pipe and became standard as weld neck, threaded and blind configurations. As equipment with integral flanges came to the oilfield, standardization became necessary for functional interchangeability. In the late 1930’s, the American Petroleum Institute (API) adopted the then ASA B16.5 flanges. For 720 psi and 960 psi applications API specified no changes to the ASA B16.5 Standard, using the 300 lb. and 400 lb. flanges respectively. For 2000, 3000, and 5000 psi applications, API specified an increase in material yield strength to the respective ASA B16.5 flanges: 600, 900, and 1500 lb. API distinguished their flanges from the original ASA flanges through the method of changing the ASA term "lb." to the API term "SERIES", (e.g. ASA 4" 900 lb. flange, 2160 psi working pressure, compared to API 4" SERIES 900 flanges, 3000 psi working pressure), dimensionally the same but differing in name, material strength, and working pressure. API issued the first specification for wellhead flanges as 6B, later incorporated into API 6A. The original flanges specified, retained the designation "6B". All API flanges adopted for wellhead use have Ring Type Joint (RTJ) facing. API flanges may have Full Face or Raised Face geometry, with either case having the specified ring groove. Most wellhead manufacturers make their 6B flanges full face. Note: The ASA (now ANSI) terms 300 lb. through 1500 lb. represented working pressures of flanges in elevated temperature service. API assumed the ambient temperature working pressure for the 300 lb. and 400 lb. CLASS and assumed ambient temperatures for 2000, 3000, and 5000 psi flanges also. ANSI has since dropped the previous ASA term "lb." and now refers to flanges by "CLASS". Today, API Spec 6A specifies standard service temperatures of -75° F to 250° F. Current API Spec 6A flanges classed as 6B by API (easily identified by the fact that they have ring grooves that accept R or RX ring gaskets) have identical dimensions with ANSI B16.5 flanges. Caution: A connection between mating ANSI and API flanges requires a rating of the connection no higher than the ANSI pressure rating. See the notes and cautions below the illustrations on the Flange Slide Rule Program pages on this web-site.

In 1945 API introduced flanges rated at 7500 psi, and by 1949 these flanges were given new material specifications, a 10,000 psi working pressure, and the classification "SERIES" 2900. Then API included them with the earlier flanges under the new specification designation STANDARD 6B. By 1957 API adopted new flanges from the Association of Well Head Equipment Manufacturers (AWHEM, See Related Links) designs to replace the "SERIES" 2900. These new 10,000 psi flanges were specified in API STANDARD 6BX. In 1961, STANDARD 6B and STANDARD 6BX were combined into STANDARD 6A, now designated Spec 6A. API included 15,000 psi and 20,000 psi flanges in more recent editions of API Spec 6A. API classes all flanges that accept BX ring gaskets as 6BX flanges. API 6BX open face flanges must have raised faces, while API 6BX Studded Face flanges may have their raised faces omitted. Most manufacturers make API 6BX studded face flanges without raised faces. API Spec 6AB, introduced in 1983, specified 30,000 psi flanged equipment. Spec 6AB has failed to achieve reaffirmation by API so it has the current status of "withdrawn". API Spec 17D, 1st edition, appeared in 1992. This specification introduced 5,000 psi working pressure Type 17SS and 17SV swivel flanges and 10,000 psi swivel flanges that connect to API Spec 6BX flanges of the same working pressure. These flanges for subsea applications have dimensions to accept BX ring gaskets. Spec 17D requires all flanges used for subsea applications to have ring grooves manufactured from, or inlayed with, corrosion resistant alloy. This specification also introduced SBX and SRX ring gaskets designed to allow reliable make-up of flanges underwater. For more information specific to API Spec 17D connectors, see About API 17D SS and SV Swivel Flanges on this Web Site. Low pressure Drilling Diverter Systems use MSS SP-44 flanges for 30" 500 psi and 30" 1,000 psi service.                

About API Spec 17D SS and SV Flanges (and Connection to API 6BX Flanges Subsea) Jump down to: 17D 10M SV Flanges Join Directly to 6BX 10M Flanges, SBX and SRX Ring Gaskets, API 17D PSL's, API 17D Blind Flanges Caution, API 17D Studded Connections, API 17D Bolt Tension, API 17D Full Bore Weld Necks, Flange Slide Rule Program

API Spec 17D, 1st. Edition dated October 30, 1992 marked the introduction of an API “Specification for Subsea Wellhead and Christmas Tree Equipment.” This Specification introduced a set of dimensions for 5M Flanges in nominal sizes 2-1/16” through 11” based on API Spec 6A, 6B Flanges, but with BX ring grooves designated in the Specification as API Type 17SS Flanges. The Specification also introduced Swivel Flanges designed to join with these new flanges, designated as API Type 17 SV Flanges, and introduced 10M Swivel Flange configurations that join directly to API Spec 6A, 6BX Flanges in sizes 1-13/16” through 13-5/8”, also designated 17 SV. API Spec 17D accepts, through direct reference, all API Spec 6A, 6BX Flanges in all sizes through 15M Working Pressure. API Spec 17D also accepts all API Spec 16A Clamp Hub connections and Clamps in all sizes through 15M Working Pressure. API Spec 17D requires all Flanges, Swivel Flanges, and Clamp Hubs used for Subsea applications to have their ring grooves either manufactured from or inlayed with Corrosion Resistant Material.

NOTE: API Spec 17D requires manufacturers to make 10M Working Pressure Swivel Flanges (Hubs and Rings) from 75K Material specified in API Spec 6A. These Swivel Flanges join to API Spec 6A, 6BX 10M Flanges made from 60K Material. API Spec 17D describes Ring Gaskets special for Subsea make-up, identified as API Type SBX and SRX pressure energized Ring Gaskets. These Ring Gaskets have identical dimensions to those Ring Gaskets identified in API Spec 6A except they all have specially located drilled holes that allow the escape of any fluids (water) trapped behind the Ring Gasket as a result of Subsea connection make-up. API Spec 17D specifies only Ring Gaskets made from Corrosion Resistant Material for all Subsea connections.

API Spec 17D references API Spec 6A for PSL Levels and specifies that all Material and finished equipment meet the minimum requirements for PSL 2, 3, or 3G, as specified by the buyer of the equipment. NOTE: The inclusion of Swivel Flanges intends to solve the problem of misaligning bolt holes in otherwise parallel flanges by allowing rotation of the Swivel Flange to bring the bolt holes into common alignment. API Spec 16A Clamp Hub connections, included in API Spec 17D by reference, also solve the problem of bolt hole alignment by totally eliminating the joining connection bolt circle. Clamp Hubs, joined by clamps, have the freedom to rotate 360° in any increment before the tightening of the Clamp to seal the connection. The Swivel Flanges in API Spec 17D have Hubs with designs similar to or identical with API Spec 16A Clamp Hubs. When Swivel Flange Hubs have identical dimensions with Clamp Hubs, and sufficient neck length exists to push the Swivel Flange Ring back away from its Hub with sufficient room to fit a Clamp, then a Clamp will secure this seemingly unorthodox connection. This Clamp connection should work with the connections shown in the Table below. API 17D SV Flange / Hub

API 16A Hub

API 16A Clamp Number

2-1/16" 5M

2-1/16" 5M

1

2-9/16" 5M

2-9/16" 5M

2

3-1/8" 5M

3-1/8" 5M

4

4-1/16" 5M

4-1/16" 5M

5

4-1/16" 10M

4-1/16" 10M

6

9" 5M

9" 5M

8

9" 10M

9" 10M

10

11" 5M

11" 5M

10

13-5/8" 10M

13-5/8" 10M

15

WOODCO USA does not offer this information as a recommendation, but knowledge of this may assist Operators in decision making should they have a problem or emergency. Click Here for more about API 16A Clamps. CAUTION: API Spec 17D specifically states, “All Flanges used on Subsea completions equipment shall be of the ring joint type designed for face-to-face make-up. The connection make-up force and external loads shall react primarily on the raised face of the flange. Therefore, at least one of the Flanges in a connection shall have a raised face.” API Spec 17D specifies an optional raised face on 17D Type SS Blind Flanges. WOODCO USA recommends that API 17D SS Blind Flanges always have raised faces. API Spec 17D makes no mention of Studded Flange connections as specified in API Spec 6A, but does not prohibit them. The implication of acceptance of API Spec 6A connections, and the fact that API Spec 6A permits the omission of raised faces on studded face 6BX Flanges will surely result in operators attempting to

install a 17D SS Blind Flange without a raised face onto an API 6A studded face connection, also without a raised face. Without using technical terms, any kind of damage to, or coating on, the face of either of the joining full face flange connectors with BX ring grooves will prevent the face to face contact intended and explained in API Spec 17D. API Spec 17D requires closure bolting tension of 67% to 70% of the yield strength of the bolts (L7 / B7); torque tables included in API Spec 17D provide torque values intended to achieve this tension. Click here for API 17D specified torque values for Fluoropolymer coated bolts and nuts connecting flanges in sub sea applications. CAUTION: API Spec 17D requires flange connection bolt tightness (tension stress in the bolt) equal to 67% to 70% of the specified minimum yield strength of L7/B7 bolts. When using some lubricants and/or anti-corrosion coatings on bolts, tightening bolts consistent with the torque tables shown in API Spec 17D may in fact produce tension closer to the actual yield strength of the bolts. Operators should use an alternate method to measure tension in the bolts to confirm the applicability of this table. The characteristic design of API 17D Swivel Flanges virtually requires their attachment to bodies by welding. All Swivel Flange illustrations in API Spec 17D show full bores, with no specified wall thickness at the end, or any weld preparation. Weld Neck Flanges shown in API Spec 17D have only restricted bores matching Line Pipe sizes. WOODCO USA offers full bore Weld Necks for all 5M Working Pressure SS and SV Flanges, and all 10M Working Pressure SV Flanges included in API Spec 17D. To view dimensions of API Spec 17D SS and SV flanges, go to the Flange Slide Rule Program on this Web Site. CAUTION: Operators should seek competent engineering advice, use Qualified Welding Procedures, and employ Qualified Welders when attaching any API Flanges made from 60K or 75K Material specified in API Spec 6A.          

API 17D, SS, FLANGE WELD NECKS 

   

API 6A FLANGE WELD NECKS