Product Overview

DEENPU API 6A Double Studded Adapter (DSA) — Through Bore with Ring Grooves on Both Sides

DEENPU Double Studded Adapter (DSA) is a critical wellhead and manifold component manufactured in strict accordance with API 6A specification. It is a solid forged or bar stock flange with a through bore, featuring a ring groove on each side, drilled and tapped bolt hole sets on both ends, and fitted with double studded bolts and nuts complete on both sides. Unlike a spacer spool or standard companion flange, the two sides of a DSA are typically different in nominal size and/or pressure rating, making it an essential adapter for connecting dissimilar API 6A flanges in wellhead assemblies, choke manifolds, kill lines, and production systems.

All DEENPU DSA products are manufactured to meet or exceed API 6A, NACE MR0175, ISO 9001, ISO 14001, and ANSI standards. They are suitable for both General Service and Sour Service (H2S) conditions, with material grades and heat treatments selected to resist sulfide stress cracking in hydrogen sulfide environments. Each DSA is supplied with full traceability documentation for every component, including material certificates, heat treatment records, hydrostatic test reports, and dimensional inspection certificates.

DEENPU DSA adapters are available in a wide range of bore sizes from 2-1/16″ to 30″ and pressure ratings from 2M (2,000 PSI) to 15M (15,000 PSI), covering all standard API 6A flange combinations. Custom configurations with non-standard bore sizes, pressure ratings, and connection types are available on request. In addition to DSAs, DEENPU also manufactures and supplies a complete range of API 6A flanges including threaded flanges, spacer spools, blind flanges, companion flanges, target flanges, test flanges, and adapter spools to meet all client requirements.

How the Double Studded Adapter Works

The Double Studded Adapter performs three essential functions in wellhead and manifold systems:

1. Flange Size and Rating Transition — The primary function of a DSA is to connect two API 6A flanges that have different nominal bore sizes, different pressure ratings, or both. For example, a DSA can connect a 2-1/16″ 5M (5,000 PSI) flange on one side to a 4-1/16″ 10M (10,000 PSI) flange on the other side. The DSA has a ring groove machined on each end face to match the ring gasket type (BX, RX, or R) of the corresponding flange. The bolt holes are drilled and tapped to accept the stud bolts and nuts of each flange. The through bore is machined to the larger of the two connected bore sizes to ensure unrestricted flow and prevent pressure restrictions. The overall thickness of the DSA is engineered to provide sufficient strength to withstand the higher of the two pressure ratings.
2. Pressure-Sealed Connection — The DSA creates a metal-to-metal seal between the two flanges using the standard API 6A ring gasket system. The ring groove on each side is precision-machined to match the ring gasket type (BX, RX, or R) with the correct groove angle and surface finish. When the flange bolts are torqued to specification, the ring gasket is compressed between the groove faces, creating a leak-tight, pressure-rated seal. The DSA itself is forged from a solid billet or bar stock, eliminating the risk of weld failure or joint leakage. The material is selected and heat-treated to achieve the mechanical properties required for the pressure rating and service conditions (General or Sour Service).
3. Structural Integrity and System Integration — The DSA acts as a rigid, integral structural member in the wellhead or manifold assembly. Its thickness is calculated to withstand the bending moments and axial loads from the connected piping, valves, and equipment. The bolt hole pattern and stud arrangement are designed to match the API 6A flange standard for each side, ensuring that the bolt loads are distributed evenly and the flange faces remain parallel under pressure. The DSA can be installed in any orientation (vertical, horizontal, or angled) and serves as a permanent or temporary connection point between wellhead components, manifold branches, or pipeline sections.

Key Features

Applications

• Wellhead assemblies — Connecting casing heads, tubing heads, and Christmas tree components with different bore sizes and pressure ratings
• Choke and kill manifolds — Adapting between high-pressure kill lines and lower-pressure production lines in well control systems
• Production manifolds — Connecting multiple wellheads to a central production header with different flange specifications
• Test and workover systems — Temporary and permanent connections for BOP stacks, test manifolds, and workover equipment
• Pipeline tie-ins — Adapting between wellhead flanges and pipeline flanges with different API and ANSI ratings
• Shipbuilding and offshore platforms — Marine and offshore piping systems requiring API 6A rated connections
• Injection systems — Water, gas, and chemical injection manifolds requiring high-pressure sour service connections
• API 6A equipment modification — Retrofitting and upgrading existing wellheads with different flange configurations

Standard DSA Specifications

All dimensions per API 6A 21st Edition. Standard ring gasket types: BX for 6BX flanges, RX for 6B flanges, R for type 6B flanges. Pressure ratings: 2M = 2,000 PSI, 3M = 3,000 PSI, 5M = 5,000 PSI, 10M = 10,000 PSI, 15M = 15,000 PSI. Other sizes and pressure ratings are available upon request. Contact us for custom configurations, non-standard bore combinations, and special material grades.

When Ordering, Please Specify

1. Top Side Flange SpecificationNominal bore size (e.g., 2-1/16″, 4-1/16″, 7-1/16″, 13-5/8″, 18-3/4″, 30″). Pressure rating (2M, 3M, 5M, 10M, 15M). Ring gasket type (BX, RX, or R).
2. Bottom Side Flange SpecificationNominal bore size. Pressure rating. Ring gasket type. Specify if the same or different from the top side.
3. Service ConditionsGeneral Service (sweet) or Sour Service (H2S). Specify H2S partial pressure, CO2 content, and temperature for sour service material selection.
4. Material GradeAPI 6A material grade: AA, BB, CC, DD, EE, FF, or HH. For sour service, specify NACE MR0175 compliant grade. For low-temperature service, specify impact test requirements.
5. Material SpecificationCarbon steel (AISI 4130/4140), low-alloy steel, or stainless steel ( duplex, super duplex). Specify for corrosive, high-temperature, or sour service environments.
6. Flange Thickness / Overall LengthStandard thickness per API 6A or custom length for specific spacing requirements. Specify if the DSA must match existing spool or adapter dimensions.
7. Through Bore RequirementStandard bore (larger of the two flange sizes) or restricted bore for flow control. Specify if a bore restriction or bore liner is required.
8. Stud Bolts and NutsASTM A193 B7 / B7M studs with A194 2H / 2HM nuts (standard). Specify if alternative materials (B8, B8M, L7) are required for temperature or corrosion resistance.
9. Coating and Surface FinishStandard machined finish or protective coating (epoxy, PTFE, zinc phosphate). Specify for corrosion protection or identification.
10. Certification RequirementsAPI 6A material certification, NACE MR0175 compliance certificate, hydrostatic test certificate, dimensional inspection report, NDT reports (UT/MPI), and third-party inspection (DNV, BV, SGS, ABS).

Custom Manufacturing & OEM Capability

• Non-Standard Bore Combinations — Any combination of API 6A bore sizes and pressure ratings not listed in the standard table. Custom engineered for specific wellhead and manifold configurations.
• Special Material Grades — Duplex stainless steel (2205, 2507), super duplex, Inconel, Monel, and other corrosion-resistant alloys for extreme sour service and high-temperature applications.
• Multi-Bore DSA — Double-bore or triple-bore configurations for dual-completion and triple-completion wellheads. Multiple through bores in a single flange body.
• Integral Valve & Instrument Ports — Machined ports for pressure gauges, temperature sensors, injection lines, and bleed valves integrated into the DSA body.
• Cladded / Overlay DSA — Inconel 625 or 316L stainless steel weld overlay on wetted surfaces for corrosion resistance without full alloy construction cost.
• Special Ring Gasket Configurations — BX, RX, R, or special groove profiles. Dual-groove configurations for redundant sealing systems.
• Alignment and Locating Features — Alignment pins, dowel holes, and locating shoulders for precise assembly and repeatable positioning in subsea and critical applications.
• Complete Wellhead Package — DSA supplied as part of a complete wellhead assembly including casing heads, tubing heads, Christmas trees, valves, and manifolds.

Quality Control & Testing Standards

• Material chemical composition verified per heat. Carbon, manganese, chromium, nickel, molybdenum, and sulfur content verified against API 6A material grade requirements.
• Material mechanical properties tested per heat including tensile strength, yield strength, elongation, and hardness per API 6A.
• Impact testing at specified temperature for low-temperature service per API 6A and ASTM A370.
• Each DSA hydrostatically tested to 1.5x rated working pressure per API 6A. Hold time, pressure, and leak rate recorded on test certificate.
• Dimensional inspection full OD, ID, thickness, ring groove dimensions, bolt circle diameter, and bolt hole pattern verified against API 6A tolerances.
• Ring groove surface finish and groove angle inspected with precision gauges and optical comparators to ensure gasket compatibility and sealing performance.
• Stud bolt holes thread inspected with go/no-go gauges and bolt hole pattern verified with coordinate measuring machine (CMM) or jig.
• NDT inspection: ultrasonic testing (UT) and magnetic particle inspection (MPI) on 100% of the forging body per API 6A.
• Material test certificates (MTC) per EN 10204 3.1 provided for all forged and bar stock materials.
• Third-party inspection and certification by DNV, BV, SGS, or ABS available upon request.

Frequently Asked Questions