Description

API 6A Double Studded Adapter Flange for Wellhead, BOP & Christmas Tree Crossover Connections

SGPE manufactures API 6A Double Studded Adapter Flanges for wellheads, Christmas Trees, BOP stacks and other high-pressure oilfield equipment that requires a compact crossover between two mating interfaces.

The oilfield industry also uses the terms DSA Flange, DSAF, Double Studded Adapter, API 6A Crossover Connector, Wellhead Adapter Flange, Wellhead Crossover Adapter and BOP Adapter Flange for this type of connection.

A DSA uses a forged pressure-containing body with precision-machined RTJ sealing faces and threaded holes for tap-end studs on both sides. Side A and Side B can therefore use different compatible nominal sizes, pressure classes, stud patterns or ring-joint configurations.

SGPE supplies standard and custom API 6A DSA Flanges for 2K, 3K, 5K, 10K and 15K systems. Typical applications include wellhead installation, BOP stack integration, completion, production, Christmas Tree replacement, surface well testing, workover and well intervention.

Depending on the mating equipment, the adapter can use API 6B or 6BX geometry, R/RX/BX ring grooves, straight or transitioned bores, AISI 4130 or 4140 forged material, project-defined material classes and different Product Specification Levels.

For sour or corrosive wells, project requirements may also include H2S service, ISO 15156 / NACE MR0175, SS316L sealing-surface protection or Alloy 625 CRA ring-groove inlay.

For an accurate quotation, provide the complete Side A × Side B connection, including nominal size, rated working pressure and ring gasket number. Clear bore, material, operating conditions, inspection requirements and any stack-height restriction can then be confirmed before quotation.

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API 6A Double Studded Adapter Flange Specifications

API 6A DSA Connection and Pressure Specifications

Engineering Note: A DSA should be defined by both mating connections, not nominal bore alone. Side A and Side B size, pressure rating, ring groove, stud pattern, clear bore and required overall thickness should be confirmed before manufacture.

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API 6A DSA Materials, Service and Quality Requirements

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What Is an API 6A Double Studded Adapter Flange?

An API 6A Double Studded Adapter Flange is a compact pressure-containing crossover used when two compatible wellhead or pressure-control components cannot connect directly.

The forged body contains a pressure bore and two precision-machined sealing faces. Each side uses threaded stud holes instead of conventional through-bolted holes, while the specified RTJ ring gasket provides the pressure seal.

Because both connection patterns sit within one short body, a DSA can solve a size or pressure-interface mismatch without adding the extra height of a longer adapter spool.

Typical installations include wellhead-to-BOP connections, tubing-head-to-Christmas-Tree connections, BOP-to-drilling-spool crossovers, replacement tree projects and temporary workover or intervention stacks.

Where vertical clearance is limited, the compact body also helps control total BOP or Christmas Tree stack height.

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API 6A DSA Connection Options

Different Size DSA Flange

A Different Size DSA Flange connects two compatible interfaces with different nominal sizes.

For example, a project may require a 4-1/16 in 10K × 2-1/16 in 10K DSA Flange between an existing wellhead and a new Christmas Tree component.

Large-bore drilling and BOP projects can require much larger crossover connections. In these cases, ring grooves, stud-hole geometry, clear bore and minimum body thickness all need to be considered together.

This type of connection is also commonly described as a Wellhead Flange Adapter, Wellhead Crossover Adapter or Double Studded Crossover Flange.

Different Pressure DSA Flange

Some brownfield and replacement projects require different pressure-class interfaces.

A typical example is a 4-1/16 in 5K × 4-1/16 in 10K DSA Flange.

The higher-rated connection does not increase the allowable working pressure of lower-rated mating equipment. The complete assembly remains limited by its applicable lowest-rated component.

This point is important when specifying a 5K-to-10K DSA Flange or high-pressure wellhead crossover for an existing system.

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2K, 3K, 5K, 10K and 15K DSA Flanges

API 6A 5K DSA Flange

A 5K DSA Flange suits many production wellhead, Christmas Tree, workover and surface well-testing projects.

Typical requirements include 5K Wellhead Adapter Flanges, API 6A 5000 PSI Crossover Flanges and custom Double Studded Adapters for equipment modification or replacement.

Before manufacture, the mating connections, RTJ rings, clear bore, material and service conditions should be confirmed.

API 6A 10K DSA Flange

A 10K DSA Flange supports high-pressure production, completion, BOP and well-testing systems.

Common RFQs include 10K BOP Adapter Flanges, 10K Wellhead Crossover Flanges, API 6A 10K Adapter Flanges and 10000 PSI Double Studded Adapters.

At this pressure level, connection geometry, ring gasket, material class, PSL, temperature, clear bore and stud arrangement become particularly important.

API 6A 15K DSA Flange

A 15K Double Studded Adapter Flange serves high-pressure wellheads, BOP interfaces, completion systems and project-specific sour-service applications.

The final review typically covers the two mating connections, RTJ geometry, forged body material, bolting, material class, PSL, NDE, hydrostatic testing, CRA requirements and available adapter thickness.

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API 6A 6B, 6BX and RTJ Connections

A DSA can use different API connections on Side A and Side B, so each face needs its own complete connection definition.

API 6B connections appear across many wellhead arrangements, while higher-pressure equipment can use API 6BX connection geometry where required by the mating interface.

For a 10K or 15K API 6BX Adapter Flange, nominal bore alone is not enough to identify the connection.

RTJ sealing also depends on the correct R, RX or BX ring groove. Two flanges with similar nominal sizes can still use different ring gasket numbers, bolt circles or stud arrangements.

For replacement work, provide the original flange designation, working pressure and ring gasket number whenever available.

This helps reduce uncertainty when sourcing an RTJ Double Studded Adapter, API 6A RTJ Adapter Flange, BX Ring Groove DSA or Replacement Wellhead Flange Adapter.

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Through-Bore and Low Stack-Height Design

The through bore should match the actual operating requirement rather than simply follow nominal flange size.

A production crossover may only need adequate flow area. By contrast, drilling, workover, coiled tubing and wireline applications can require a defined minimum drift so tools or tubulars can pass through the adapter.

Stack height is equally important.

An excessively thin DSA can create interference between opposing stud holes, required thread engagement, RTJ grooves and the internal bore transition. The pressure-containing body must also retain adequate section thickness.

For installations with restricted clearance, provide the maximum allowable DSA thickness or maximum BOP / Christmas Tree stack height with the RFQ.

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Forged DSA Materials and Material Classes

Pressure-containing DSA bodies can use project-approved forged alloy steels such as AISI 4130 or AISI 4140, depending on design and end-user requirements.

An AISI 4130 DSA Flange is common in wellhead and pressure-control applications, but pressure rating alone does not determine the correct material.

Material selection also depends on body section thickness, temperature, retained fluid, material class, PSL and sour-service requirements.

For corrosive wells, useful project information includes H2S, CO2, chlorides, produced water, operating pressure, temperature and corrosion specification.

Providing these details early reduces the risk of material changes later in the project.

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Sour Service DSA Flanges for H2S Wells

SGPE can supply project-specific Sour Service API 6A Double Studded Adapter Flanges for H2S-containing wellhead and pressure-control systems.

Sour service can affect body material, hardness limits, heat treatment, bolting, sealing surfaces and inspection requirements. Where applicable, the project specification can also reference ISO 15156 / NACE MR0175.

Typical applications include sour gas wells, H2S-containing oil production, high-pressure BOP crossovers, Christmas Tree modifications and replacement wellhead equipment.

H2S service should be identified before material procurement. Changing a general-service adapter to sour service after manufacturing starts can affect material selection, heat treatment, inspection and cost.

For highly corrosive environments, CRA protection may also be required at critical RTJ sealing areas.

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SS316L and Alloy 625 CRA Ring-Groove Options

The RTJ sealing area can require additional corrosion resistance in demanding production environments.

SGPE can review SS316L or Alloy 625 CRA ring-groove configurations where specified.

An Alloy 625 DSA Flange or CRA Inlay Wellhead Adapter can be considered for sour wells, CO2-rich production, offshore applications and other corrosive environments.

The final CRA grade, inlay or overlay process and inspection scope should follow the approved corrosion specification rather than one standard material solution for every service condition.

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Tap-End Studs, Nuts and Bolting

Because a Double Studded Adapter uses threaded holes on both mating faces, tap-end studs form part of the connection design.

Stud diameter, thread form, engagement depth, length, material and nut grade depend on the mating interface and service conditions.

Pressure, temperature and sour service can also affect bolting requirements.

When included in the purchase scope, SGPE can supply the API 6A DSA Flange complete with matching tap-end studs and nuts, reducing the risk of incompatible bolting being sourced separately.

Project-specified surface protection can also be supplied where required.

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API 6A Double Studded Adapter Flange Applications

Wellhead-to-BOP Crossover

A Wellhead to BOP Adapter Flange provides the transition between an existing wellhead and compatible Annular BOP, Ram BOP or drilling-spool equipment.

These projects often combine a large bore, high working pressure and restricted vertical clearance. Both mating interfaces, minimum clear bore and maximum installation height should therefore be considered together.

Large-bore BOP Stack Crossover Adapters can also support rig upgrades, replacement BOP packages and modifications to pressure-control equipment.

Christmas Tree Installation and Replacement

A Christmas Tree Adapter Flange can connect a tubing head or tubing-head adapter to a production tree when the mating interfaces differ.

This is especially useful in brownfield projects.

If the existing wellhead remains serviceable but a replacement Christmas Tree uses another flange interface, a custom DSA can provide the required transition without forcing the operator to replace additional equipment.

Surface Well Testing

Surface well-testing packages can combine equipment from different systems or service fleets.

A Double Studded Adapter can provide a compact crossover between compatible wellhead, surface test tree, flowhead, valve, manifold and other pressure-control interfaces.

Working pressure, clear bore, RTJ connection and service conditions should be confirmed before manufacture.

Workover and Well Intervention

Workover, coiled tubing, wireline and slickline operations often require temporary pressure-control equipment above an existing production wellhead or Christmas Tree.

A compact DSA can minimize added stack height while providing the required interface.

For intervention work, the clear bore is equally important because tools may need to pass through the adapter.

Offshore and Brownfield Wellhead Upgrades

Offshore facilities and mature oilfields often contain equipment installed at different times.

A Custom DSA Flange or Replacement Wellhead Adapter Flange can connect a new BOP, Tree or intervention component to a compatible existing wellhead.

This makes the product particularly useful for MRO, retrofit and replacement projects where the original crossover is obsolete or no longer available.

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DSA Flange vs Adapter Spool vs Spacer Flange

Choose a Double Studded Adapter Flange when the project needs a compact crossover and stack height matters.

Choose an API 6A Adapter Spool when the bore transition requires more length or additional equipment separation.

A Spacer Flange or Spacer Spool is more suitable when the main requirement is spacing rather than a major connection change.

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Custom and Replacement API 6A DSA Flanges

Many replacement projects begin without a complete original drawing.

The original manufacturer may no longer support the equipment, or a new BOP, Christmas Tree or intervention package may use a different interface from the existing wellhead.

Verified field information can often support the initial technical review.

Clear photographs, equipment nameplates and accurate field measurements help identify which dimensions still require confirmation.

This makes custom manufacturing especially useful for Replacement DSA Flanges, Obsolete Wellhead Adapters, Replacement BOP Adapter Flanges and Brownfield Christmas Tree retrofit projects.

When the original drawing is unavailable, both mating interfaces should be verified independently rather than copying only the outside dimensions of the old adapter.

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Manufacturing and Quality Control

Engineering Review

Before production, SGPE reviews the Side A and Side B connections, rated working pressures, RTJ grooves, clear bore, material requirements, operating temperature, PSL and stack-height restrictions against the approved project data. This step helps confirm interface compatibility before manufacturing starts.

Forging and Material Control

SGPE selects the forging according to the approved design, pressure class and service conditions. The production team controls material identification and maintains heat-number traceability throughout the manufacturing process.

Heat Treatment and Machining

The forging undergoes the required heat-treatment process before rough and finish machining. CNC machining then forms the pressure bore, sealing faces, RTJ ring grooves and threaded stud holes to the specified dimensions.

Nondestructive and Dimensional Inspection

SGPE carries out the required UT, MT, PT and dimensional inspections according to the approved inspection plan. Inspectors verify critical dimensions such as the bore, bolt circle, stud pattern, ring groove, mating-interface geometry and overall thickness.

CRA Inlay or Overlay

When the project requires corrosion-resistant sealing surfaces, SGPE applies the specified CRA inlay or overlay to the required areas. The team then performs the applicable inspection and final machining to achieve the specified RTJ sealing geometry.

Hydrostatic Testing and Final Documentation

SGPE performs the required hydrostatic pressure test before final inspection and product release. After testing, the team completes product identification, surface protection and the agreed manufacturing documentation, which may include MTRs, NDE reports, dimensional records, hydrotest reports, COC, ITP and MDR documents.

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Inspection and Documentation for API 6A DSA Orders

Third-party inspection, witness points and documentation requirements should be defined before order placement so the inspection plan and manufacturing records can be prepared correctly from the beginning.

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Why Source API 6A Double Studded Adapter Flanges from SGPE?

SGPE focuses on oilfield drilling, wellhead, Christmas Tree, BOP and pressure-control equipment. This allows a DSA to be considered as part of the complete equipment interface rather than as an isolated industrial flange.

Many Double Studded Adapter requirements are project-specific. Connection sizes, pressure classes, bore profiles, stack-height restrictions, sour-service conditions and replacement interfaces can all change the final design.

For new projects, customers can provide a drawing or complete connection specification. For replacement work, verified field dimensions, equipment nameplates and mating-equipment drawings can support the initial review.

SGPE also supplies related API 6A Adapter Spools, Spacer Spools, Wellhead Flanges, Tubing Head Adapters, Wellhead Crosses, Wellhead Tees, Tree Caps, Casing Heads, Tubing Heads, Gate Valves, Ball Valves, Choke Valves and Check Valves.

For projects involving several mating components, this broader API 6A product range can simplify interface coordination and purchasing.

Project documentation can include MTRs, dimensional reports, NDE records, hydrostatic test reports, COC, ITP, TPI and agreed MDR documentation.

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How to Get an Accurate API 6A DSA Flange Price and Quotation

The price of an API 6A Double Studded Adapter Flange cannot be determined from nominal size alone.

Side A and Side B define the basic connection geometry. Working pressure and adapter thickness affect forging size and machining. Material class, PSL and sour-service requirements can change both material and inspection costs.

Additional requirements such as Alloy 625 CRA inlay, SS316L sealing surfaces, tap-end studs and nuts, NDE, hydrostatic testing, TPI and project documentation can also affect the quotation.

For example:

Please quote one 4-1/16 in DSA.

does not provide enough information for an accurate offer.

A better RFQ would be:

4-1/16 in 10K × 2-1/16 in 10K API 6A DSA Flange, specified RTJ connections, complete with studs and nuts, sour service, project-required material class and PSL, quantity 2 sets.

That provides enough information to begin both technical review and commercial quotation.

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API 6A DSA Flange RFQ Data Sheet

If some parameters are unavailable, send the existing equipment nameplate, clear photographs and any available drawing. Missing interface details can then be identified during the initial technical review.

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Related API 6A Wellhead and Pressure-Control Equipment

A Double Studded Adapter is often purchased together with other mating wellhead components.

For longer crossover transitions, an API 6A Adapter Spool may be more suitable. Where the main requirement is additional spacing, an API 6A Spacer Spool can provide the required installation height.

Related connection equipment can also include API 6A Wellhead Flanges, Tubing Head Adapters, Wellhead Crosses, Wellhead Tees and Tree Caps.

For production and pressure-control packages, SGPE also supplies API 6A Gate Valves, Ball Valves, Check Valves and Choke Valves.

These product names should be used as natural internal-link anchor text when the corresponding SGPE product pages are available.

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Frequently Asked Questions About API 6A Double Studded Adapter Flanges

1. What is an API 6A Double Studded Adapter Flange?

An API 6A Double Studded Adapter Flange, also called a DSA Flange, DSAF, Double Studded Adapter or API 6A Crossover Connector, provides a compact pressure-containing connection between two compatible wellhead or pressure-control interfaces. Engineers commonly use it when the mating components have different nominal sizes, pressure ratings, stud patterns or RTJ connection arrangements.

A DSA uses studded connections on both faces and normally adds less stack height than an adapter spool. This compact design makes it suitable for wellhead-to-BOP connections, Christmas Tree installation, workover stacks and brownfield wellhead upgrades, especially where vertical clearance is limited.

2. Where are API 6A Double Studded Adapter Flanges commonly used?

Operators use API 6A Double Studded Adapter Flanges in drilling, well completion, production, surface well testing, workover and well-intervention operations. Typical applications include connecting a wellhead to a BOP stack, adapting a tubing head to a Christmas Tree, connecting BOP equipment to a drilling spool and integrating temporary pressure-control equipment.

A Wellhead Adapter Flange or BOP Crossover Adapter can also solve interface problems during coiled tubing, wireline and slickline operations. Offshore platforms and mature oilfields often use custom DSA Flanges when existing equipment does not directly match a new wellhead, BOP or intervention package.

3. What API flange and RTJ connections can an API 6A DSA Flange use?

An API 6A DSA Flange can use applicable API 6B or API 6BX connection geometry together with the corresponding R, RX or BX ring groove, depending on the mating equipment and project requirements.

Side A and Side B may use different flange sizes, pressure ratings or ring gasket numbers, so each face requires separate confirmation. When ordering an RTJ Double Studded Adapter, API 6A 6BX Adapter Flange or BX Ring Groove DSA, provide the flange designation, working pressure, stud arrangement and ring gasket number for both sides.

This becomes especially important in replacement wellhead and BOP crossover projects.

4. What working pressures are available for API 6A DSA Flanges?

SGPE supplies API 6A DSA Flanges for project requirements including 2,000 psi, 3,000 psi, 5,000 psi, 10,000 psi and 15,000 psi, commonly described as 2K, 3K, 5K, 10K and 15K DSA Flanges.

These pressure classes support production wellheads, Christmas Trees, BOP stacks, completion equipment and surface well-testing systems.

Because not every nominal size matches every pressure class, customers should specify the complete Side A and Side B interfaces. For 10K and 15K Double Studded Adapter Flanges, SGPE also reviews the connection geometry, material class, PSL, RTJ configuration, clear bore and inspection requirements.

5. Can SGPE manufacture a custom different-size DSA Flange?

Yes. SGPE manufactures custom different-size DSA Flanges for wellhead, BOP, Christmas Tree and pressure-control crossover applications.

For example, a project may require a 4-1/16 in 10K × 2-1/16 in 10K Double Studded Adapter to connect an existing wellhead to a new Christmas Tree component.

Large-bore BOP and drilling projects may require much larger crossover combinations. In these cases, SGPE checks the ring-joint geometry, stud-hole arrangement, clear bore, bore transition and available body thickness before confirming the design.

Customers may also refer to these products as Wellhead Flange Adapters, BOP Adapter Flanges or Wellhead Crossover Adapters.

6. Can an API 6A DSA connect two different pressure ratings?

Yes, certain API 6A DSA configurations can connect two different pressure-class interfaces after engineering review.

For example, a brownfield upgrade may require a 5K-to-10K DSA Flange between an existing wellhead and a new component with a different connection rating.

However, the higher-rated side does not increase the allowable working pressure of the lower-rated equipment. The lowest-rated applicable component still limits the complete pressure-containing assembly.

For this reason, SGPE reviews different-pressure DSA applications together with the mating wellhead, BOP or Christmas Tree equipment.

7. Does SGPE supply 10K and 15K Double Studded Adapter Flanges?

Yes. SGPE supplies 10K and 15K API 6A Double Studded Adapter Flanges for high-pressure wellheads, BOP stacks, Christmas Trees, completion systems and surface well-testing equipment.

For these high-pressure applications, SGPE reviews the mating interfaces, RTJ ring grooves, forged body material, material class, PSL, clear bore, bolting and inspection requirements.

Sour-service or offshore projects may also require tighter hardness control, additional NDE, hydrostatic testing or corrosion-resistant sealing surfaces.

8. Can SGPE supply Sour Service DSA Flanges for H2S wells?

Yes. SGPE can manufacture Sour Service API 6A DSA Flanges for H2S-containing oil and gas wells according to the approved project requirements.

The project may specify an API 6A material class together with applicable ISO 15156 / NACE MR0175 requirements. H2S concentration, CO2, operating pressure, temperature, produced fluids and corrosion conditions can all influence the final material, hardness, heat treatment, bolting and sealing-surface design.

Typical applications include high-pressure sour gas wells, BOP crossover connections, Christmas Tree modifications and replacement wellhead projects.

9. Are Alloy 625 or SS316L CRA ring-groove options available?

Yes. SGPE can supply project-specific Alloy 625 or SS316L CRA ring-groove options when the RTJ sealing area requires additional corrosion resistance.

Operators commonly consider these solutions for sour wells, CO2-rich production, offshore installations and other corrosive environments.

An Alloy 625 DSA Flange or CRA Inlay Wellhead Adapter should match the actual corrosion conditions rather than rely only on pressure rating. The approved project specification should define the final CRA grade, inlay or overlay process and inspection requirements.

10. What is the difference between a Double Studded Adapter Flange and an API 6A Adapter Spool?

A Double Studded Adapter Flange uses a shorter body and works well when the project needs a compact crossover with minimal added stack height. Operators commonly install it between wellheads, BOP stacks and Christmas Trees where vertical space is limited.

An API 6A Adapter Spool provides more body length and therefore allows more room for a larger internal bore transition or greater separation between two mating components.

Both products can connect different sizes or interfaces. The required bore profile, connection geometry and available installation height usually determine which option fits the project better.

11. Can SGPE manufacture a Replacement DSA Flange without the original drawing?

Yes, in many cases SGPE can review a Replacement DSA Flange even when the original drawing is unavailable.

Customers can provide the Side A and Side B sizes, pressure ratings, ring gasket numbers, clear bore, bolt circle, stud quantity, stud diameter, existing face-to-face thickness and equipment nameplate.

Clear photographs, field measurements and drawings of the new mating equipment can also help SGPE identify the existing connection.

This approach works particularly well for replacement wellhead adapters, obsolete DSA Flanges, BOP crossover replacements and brownfield Christmas Tree upgrades.

12. What information should I send for an API 6A DSA Flange quotation?

For an accurate API 6A Double Studded Adapter Flange quotation, send SGPE the complete Side A and Side B connection information, including nominal sizes, rated working pressures and ring gasket numbers.

Also provide the mating equipment, minimum clear bore and any maximum stack-height restriction. When available, include the operating temperature, material class, PSL, general or sour-service requirement, H2S or CO2 conditions, CRA requirement, studs and nuts, quantity, NDE, hydrostatic testing, third-party inspection and documentation requirements.

A GA drawing, existing equipment drawing, nameplate or clear field photograph will help SGPE review the connection more efficiently and prepare the appropriate technical proposal and quotation.

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Request an API 6A DSA Flange Quotation from SGPE

If you need an API 6A Double Studded Adapter Flange (DSA / DSAF) for wellhead, BOP, Christmas Tree, workover, well testing, intervention or brownfield replacement projects, send SGPE your connection requirements for review.

To prepare an accurate offer, please provide the Side A and Side B sizes, rated working pressures and ring gasket numbers, together with the mating equipment and minimum clear bore. If applicable, also include the maximum stack height, temperature, material class, PSL, sour-service or CRA requirements, studs and nuts, quantity, inspection scope and required documentation.

For replacement DSA Flanges, you can also send the existing equipment nameplate, GA drawing, field dimensions or clear photographs if the original drawing is unavailable.

Based on the supplied technical data, SGPE will review the connection compatibility, material and project requirements, then provide you with the corresponding technical proposal and quotation.

Email:  info@sgpe.com
Tel / WhatsApp:  +86 186-1599-5239