MSS SP-44 Flanges Suppliers

Dimensions & Pressure Ratings

MSS SP-44 Flanges Suppliers

MSS SP-44 Standard Flanges: Dimensions | Specifications | Material Grade | Standards | About MSS SP-44 | All Product Types

MSS SP-44 flanges are high-strength forged steel flanges developed specifically for pipeline systems in the oil, gas, petrochemical, and offshore sectors. This standard was established by the Manufacturers Standardization Society (MSS) to define the requirements for Steel Pipeline Flanges in sizes NPS 1½″ to 24″ and pressure classes 150, 300, 600, and 900, making them highly suitable for demanding high-pressure and high-temperature systems.

Unlike general-purpose flange standards, MSS SP-44 strictly governs the dimensions, facing types (Raised Face / RTJ), tolerances, bolting patterns, and thicknesses for Welding Neck and Blind Flanges. These flanges are typically Series A and are often used as equivalents to ASME B16.47 Series A flanges, especially for API pipelines and transmission lines.

At Nutech, we manufacture and export MSS SP-44 flanges in full compliance with global specifications. All flanges undergo precision machining, dimensional inspection, and hydro testing, and are supplied with EN 10204 3.1 / 3.2 certification, including NACE MR0175, PED, and IBR approval where required. These flanges are available with face finishes like stock finish, spiral serrated, or smooth finish, ensuring optimal gasket compatibility.

We also offer custom drilling patterns, coating options (black paint, anti-rust varnish, hot-dip galvanizing), and special packaging for export shipments. Our SP-44 flange solutions are engineered for performance and reliability in critical service environments, with 100% traceability and compliance to project documentation.

MSS SP-44 Standard Flanges – Dimensions, Tolerances, and Pressure Ratings for High-Pressure Pipeline Applications

For complete technical details, including dimensions, pressure rating classes, weight charts, sizes, tolerances, and material specifications of our MSS SP-44 Standard Flanges, please download the full Catalog PDF below.

Nutech is a Leading Manufacturer & Exporter of MSS SP-44 Weld Neck and Blind Flanges in Class 150 to 900 with Precise Facing Types and Bolting Dimensions

Technical Specifications of MSS SP-44

Specification Details
Standard MSS SP-44 (Steel Pipeline Flanges)
Flange Types Weld Neck (WN), Blind (BL)
Size Range 1½″ to 24″ NPS (DN40 to DN600)
Pressure Ratings Class 150, 300, 400, 600, 900
Face Types Raised Face (RF), Ring Type Joint (RTJ)
Design Criteria Series A dimensions, ANSI B16.5 bolt patterns, pipeline-focused tolerance requirements
Manufacturing Process Forged, Machined, Heat Treated, Stress Relieved (as required)
Testing & Inspection Hydrostatic Testing, PMI, UT/MPI, Dimensional & Visual Inspection
Marking Standard per MSS SP-25 – Size, Rating, Heat No., Material, Manufacturer
Documentation EN 10204 3.1 / 3.2, NACE MR0175, ISO 9001, PED 2014/68/EU
Application Industries Oil & Gas, Petrochemical, Power Generation, Water Treatment, Food & Beverage, Fire Protection Systems, Pulp & Paper, Shipbuilding, HVAC, Offshore
Origin Made in India (by Nutech Overseas)
Export Network USA, Europe, and Middle East

Complete Material Grade Chart - Class 150 MSS SP-44

Material Category MSS SP-44 Flange Grades
Stainless Steel MSS SP-44 Flange ASTM A182 F304 / F304L / F304H, F316 / F316L / F316Ti, F310, F309S, F317 / F317L, F321 / F321H, F347 / F347H, F904L, ASTM A351 CF3 / CF3M / CF8 / CF8M / CF8C, DIN 1.4301, 1.4306, 1.4307, 1.4311, 1.4401, 1.4404, 1.4408, 1.4409, 1.4541, 1.4571, 1.4550, 1.4435, 1.4539
Duplex Steel MSS SP-44 Flange ASTM A182 F51 / F52 / F53 / F54 / F55 / F57 / F59 / F60 / F61, UNS S31803 / S32205
Super Duplex Steel MSS SP-44 Flange ASTM A182 F53 / F55 / F57 / F59 / F60 / F61, UNS S32750 / S32760
Carbon Steel MSS SP-44 Flange ASTM A105 / A105N, ASTM A350 LF2, ASTM A694 F52 / F56 / F60 / F65 / F70 / F80, ASTM A216 WCB, DIN 1.0460 / 1.0402 / 1.0619, Die Steel, Mild Steel
Alloy Steel MSS SP-44 Flange ASTM A182 F5 / F9 / F11 / F12 / F22 / F91, AISI 4130 / 4140
Nickel Alloy MSS SP-44 Flange Nickel 200 / 201, ASTM B564
Monel MSS SP-44 Flange Monel 400 (UNS N04400), Monel K500 (UNS N05500), ASTM B564
Inconel MSS SP-44 Flange Inconel 600 / 601 / 625 / 690 / 718 / 783 / X750, ASTM B564
Incoloy MSS SP-44 Flange Incoloy 800 / 800H / 800HT (UNS N08800), Incoloy 825 (UNS N08825), Incoloy 925, ASTM B564
Hastelloy MSS SP-44 Flange Hastelloy C276 (UNS N10276), C22 (UNS N06022), C4, C2000, B2, B3, X, ASTM B564
Alloy 20 MSS SP-44 Flange Alloy 20 / 20Cb-3, Carpenter® 20, ASTM B462
254 SMO MSS SP-44 Flange SMO 254 / 6Mo, UNS S31254, DIN 1.4547, ASTM A182
Copper Nickel MSS SP-44 Flange Copper Nickel 90/10 (C70600), 70/30 (C71500), UNS C71640, ASTM B61 / B62 / B151 / B152
Copper MSS SP-44 Flange TP1, TP2, T1, T2, C10100–C12300, C14200–C17200, C21000–C71520, including C10930, C11000, C11400, C12000, C12200, C26000, C28000, C33000, C44300, C70600, etc.
Brass MSS SP-44 Flange Grades 3602, 2604, H59, H62, etc.
Aluminium MSS SP-44 Flange Aluminium Grades 5052, 6061, 6063, 2017, 7075, etc.
Titanium MSS SP-44 Flange ASTM B381 Gr.1 / Gr.2 / Gr.4 / Gr.5 / Gr.7, UNS R50250 / R50400 / R50550 / R50700 / R52400 / R53400 / R56320 / R56400
Other Special Grades Al6XN, Tin Bronze, Aluminium Bronze, Lead Bronze, Nimonic 75 / 80A / 90

International Flange Standards We Manufacture & Supply

What is MSS SP-44 and how does it differ from other flange standards?

MSS SP-44 is a technical standard published by the Manufacturers Standardization Society (MSS) that defines the requirements for steel pipeline flanges, specifically Weld Neck and Blind flanges used in high-pressure transmission systems such as oil & gas pipelines.

Key differences between MSS SP-44 and other flange standards like ASME B16.5 include:

  • Application Focus:

    MSS SP-44 is tailored for pipeline applications, while ASME B16.5 serves general industrial piping systems.

  • Size & Pressure Range:

    Covers NPS 1½″ to 24″ and Class 150, 300, 400, 600, 900 pressure ratings. For larger diameters, it aligns with ASME B16.47 Series A.

  • Dimensions & Tolerances:

    MSS SP-44 specifies more robust wall thicknesses, tighter dimensional tolerances, and heavier-duty designs than B16.5 for enhanced durability.

  • Facing & Bolt Patterns:

    Includes Raised Face (RF) and Ring Type Joint (RTJ) options, with bolt-hole patterns matching pipeline standards.

This standard ensures that the flanges meet stringent pipeline integrity requirements, particularly in high-pressure and high-temperature operating conditions.

What type of gaskets are used with MSS SP-44 flanges?

MSS SP-44 flanges are typically supplied with Raised Face (RF) or Ring Type Joint (RTJ) facing, and each face type requires compatible gaskets to ensure a leak-proof seal under pressure.

Here’s how gasket selection works for MSS SP-44:

  1. For Raised Face (RF) Flanges:
    • Spiral wound gaskets (most commonly used)
    • Metal jacketed gaskets
    • Compressed fiber gaskets (for low-pressure systems)
    • Kammprofile gaskets (for better sealing in critical services)
  2. For Ring Type Joint (RTJ) Flanges:
    • Metallic RTJ gaskets (typically octagonal or oval ring types)
    • Made from soft iron, SS, or low alloy steel, depending on application
  3. Key Considerations:
    • Gasket material must match the process media and pressure rating
    • Proper surface finish on the flange face is essential for seal integrity
    • Gasket thickness and width must match MSS SP-44 dimensions

Choosing the right gasket ensures long-term performance, pressure containment, and safety in demanding oil & gas or petrochemical pipelines.

What are the dimensional tolerances specified in MSS SP-44 flanges?

MSS SP-44 specifies strict dimensional tolerances to ensure interchangeability, consistent performance, and integrity in high-pressure pipeline systems. These tolerances are especially critical during site installation and welding.

Key tolerance criteria include:

  • Flange Thickness (T):
    • Tolerance: ±1.6 mm (±0.0625″)
  • Bolt Circle Diameter (BCD):
    • Tolerance: ±1.5 mm
    • Ensures perfect bolt alignment across mating flanges
  • Outside Diameter (OD):
    • Varies based on flange size
    • Typically within ±3.0 mm
  • Bolt Hole Diameter:
    • Tolerance: ±0.8 mm
    • Must accommodate bolting and gasket compression tolerances
  • Facing Finish:
    • For Raised Face: 3.2–6.3 μm (125–250 AARH)
    • For RTJ: As per ASME B16.20, depending on ring type
  • Squareness and Parallelism:
    • Machined surfaces must maintain flatness and parallelism
    • Checked via dial indicators during QC

These tight tolerances reduce the risk of leaks, misalignments, and installation errors — especially important for pipeline systems operating under high stress and thermal cycling.

Are MSS SP-44 flanges compatible with ASME B16.5 flanges?

Yes, MSS SP-44 flanges are partially compatible with ASME B16.5 flanges under specific conditions, particularly in terms of bolt-hole patterns and pressure ratings. However, there are important technical differences that must be considered:

Compatibility Aspects:

  1. Bolt Circle Diameter (BCD):
    • MSS SP-44 and ASME B16.5 Class 150–900 use identical BCDs for corresponding sizes, ensuring bolt-up compatibility.
  2. Gasket Seating Surface:
    • Both standards support RF and RTJ facings; gasket compatibility is typically not an issue.

Differences to Watch:

  1. Flange Thickness & Weight:
    • MSS SP-44 flanges are usually thicker and heavier, designed for rugged pipeline service.
  2. Tolerances and Hub Dimensions:
    • The hub dimensions (length and bore) may differ, impacting weld joint design.
  3. Design Intent:
    • MSS SP-44 is pipeline-focused; ASME B16.5 is general-purpose for process piping.

Flanges can often be mated across these standards, but a detailed dimensional review is necessary for high-integrity applications. Always confirm with engineering drawings and relevant specs before mixing standards.

What materials are recommended for MSS SP-44 flanges in different service conditions?

Material selection for MSS SP-44 flanges depends on the pressure rating, temperature range, and chemical compatibility of the media in the pipeline. The standard allows flanges to be manufactured from carbon steel, low-temperature carbon steel, stainless steel, and even alloy grades where required.

Common Materials & Their Service Suitability:

  1. ASTM A105 (Carbon Steel):
    • Ideal for standard temperature-pressure service.
    • Suitable for oil, gas, and water pipelines up to ~500°C.
  2. ASTM A350 LF2 (Low-Temp Carbon Steel):
    • Used in cryogenic and cold environments (down to –46°C).
    • Common in LNG and offshore pipelines.
  3. ASTM A182 F304/F316 (Stainless Steel):
    • For corrosive environments like chemical or marine applications.
    • Provides resistance to acids, salts, and moisture.
  4. ASTM A694 F52 / F60 / F65 (High-Yield Carbon Steel):
    • Designed for high-pressure transmission pipelines.
    • Offers excellent strength-to-weight ratio.

Additional Considerations:

  1. Always ensure material meets NACE MR0175 / ISO 15156 for sour service.
  2. For critical applications, impact testing, chemical composition, and heat treatment traceability must be documented per project specs.

Material selection directly affects flange performance, weldability, and service life — making it a crucial engineering decision.

Which countries does Nutech export MSS SP-44 flanges to?

Nutech is a trusted global manufacturer and exporter of MSS SP-44 standard flanges, supplying critical pipeline components to a wide range of international markets. Our export network spans across oil & gas hubs, infrastructure projects, and industrial zones worldwide.

We regularly export MSS SP-44 Weld Neck and Blind Flanges to:

  • USA – Including Gulf Coast refineries and pipeline networks
  • Saudi Arabia – For oilfield infrastructure and Aramco-linked projects
  • UAE – Particularly Dubai and Abu Dhabi EPC contractors
  • Qatar – LNG terminals and gas transport systems
  • Kuwait – Petrochemical plants and water transmission lines
  • Egypt – Oil pipelines and public utility sectors
  • Iraq – Downstream and midstream pipeline segments
  • Indonesia, Malaysia, Vietnam – Southeast Asian energy markets
  • Europe – Including Germany, Italy, Spain & the Netherlands

With certifications, fast lead times, and compliance with international standards, Nutech ensures secure and consistent deliveries for large-scale and urgent project requirements.

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