What is MSS SP 44
MSS SP 44 covers pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for steel pipeline flanges. Welding neck flanges are forged steel, and blind flanges may be made from forged steel or steel plate.
MSS SP 44 :2016 pdf free download:
MSS SP 44 Pressure-Temperature Ratings & Size
Flanges covered by this S tandard Practice shall be designated as one of the following: Class 1 50 , 300 , 400 , 600 , or 900 .
The specific relationship between NPS and DN sizing, for flanges in MSS SP 44, are as follows:
| NPS | 12 | 14 | 16 | 18 | 20 | 22 | 24 | 26 | 28 | 30 | 32 | 34 | 36 |
| DN | 300 | 350 | 400 | 450 | 500 | 550 | 600 | 650 | 700 | 750 | 800 | 850 | 900 |
| NPS | 38 | 40 | 42 | 44 | 46 | 48 | 50 | 52 | 54 | 56 | 58 | 60 | / |
| DN | 950 | 1000 | 1050 | 1100 | 1150 | 1200 | 1250 | 1300 | 1350 | 1400 | 1450 | 1500 | / |
MSS SP 44 MATERIALS
The manufacturer must choose the steel for making these flanges to meet the following requirements:
- All materials used for flanges must be “killed” steel.
- Welding neck flanges should be made from forgings. Blind flanges can be made from forged steel or steel plates.
- The chosen material must meet the specified chemistry limits in Table:
| Element | C | Mn | P | S | Si | Cu | Ni | Cr | Mo | V | Nb | B | Cu+Ni+Cr+Mo | |
| Limit (%) | Min. | / | 0.60 | / | / | 0.15 | / | / | / | / | / | / | / | / |
| Max. | 0.30 | 1.60 | 0.025 | 0.025 | 0.35 | 0.40 | 0.40 | 0.30 | 0.12 | 0.11 | 0.05 | 0.001 | 1.00 | |
- The grade requirements of Table
| GRADE | YIELD POINT (Min.) | TENSILE STRENGTH (Min.) |
ELONGATION 50 mm (2 in.) (Min.%) |
||
| MPa | ksi | MPa | ksi | ||
| F36 | 248(a) | 36(a) | 414 | 60 | 20 |
| F42 | 290 | 42 | 414 | 60 | 20 |
| F46 | 317 | 46 | 414 | 60 | 20 |
| F48 | 331 | 48 | 427 | 62 | 20 |
| F50 | 345 | 50 | 441 | 64 | 20 |
| F52 | 359 | 52 | 455 | 66 | 20 |
| F56 | 386 | 56 | 469 | 68 | 20 |
| F60 | 414 | 60 | 517 | 75 | 20 |
| F65 | 448 | 65 | 531 | 77 | 18 |
| F70 | 483 | 70 | 552 | 80 | 18 |
| F80 | 550 | 80 | 620 | 90 | 16 |
- The Certified Material Test Report (CMTR) should include both ladle and product analyses. The product analysis is subject to over/under tolerances as specified in ASTM A961/A961M.
- The steel used must be suitable for field welding to other flanges, fittings, or pipe manufactured according to ASTM A105, ASTM A53, ASTM A106, ASTM A350, ASTM A381, ASTM A516, ASTM A537, ASTM A694, ASTM A707, or API Specification 5L.
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Hardness shall be HBW 23 5 as a maximum.
What is the difference between ASME B16 and MSS SP 44?
| Comparison Item | ASME B16 | MSS SP-44 |
| Scope and Application | Includes several standards related to flanges, such as ASME B16.5 (for pipe flanges and flanged fittings up to 24 inches) and ASME B16.47 (for large diameter steel flanges). The ASME B16 standards cover a broad range of flange sizes, pressure ratings, and materials, widely used in the oil, gas, and chemical industries. | Specifically covers large-diameter steel flanges ranging from 14 inches to 60 inches, primarily intended for high-pressure pipeline service. MSS SP-44 has a narrower scope compared to ASME B16 and is often used in pipeline applications where large diameters and high pressures are required. |
| Size Range | Covers flanges ranging from small diameters to large diameters, including flanges up to 24 inches (ASME B16.5) and large diameters from 26 inches to 60 inches (ASME B16.47). | Focuses on flanges from 14 inches to 60 inches, with an emphasis on large diameters. |
| Pressure Classes | Offers a broader range of pressure classes, typically including 150, 300, 400, 600, 900, 1500, and 2500 (depending on the specific ASME B16 standard). | Generally includes pressure classes 150, 300, 400, 600, and 900, but MSS SP-44 specifically addresses the needs of high-pressure pipelines. |
| Materials | Specifies a variety of materials, including carbon steel, stainless steel, and alloy steels, suitable for different applications. | Primarily covers carbon steel flanges but may also include materials like stainless steel and alloy steels for specific applications. |
| Design and Dimensional Differences | The dimensional and design requirements for flanges in the ASME B16 standards are more comprehensive and standardized for a wide range of industrial applications. | Focuses on specific design and dimensional criteria for large-diameter pipeline flanges, which may differ slightly from those found in the ASME B16.47 series, especially regarding bore sizes and thickness. |
| Usage | Widely used in various industries for general-purpose piping systems. | More commonly used in pipeline applications, especially where large diameters and high pressures are involved. |
MARKING
Flanges shall be marked in accordance with the rules established in MSS SP-25 . In addition, the letters, “PL” shall precede the grade symbol marking. The grade symbol marked on the Welding Neck Flange shall designate the grade of material in the welding end of the hub .
Flange Facing Finish
The finish of contact faces of pipe flanges shall be judged by visual comparison with Ra S tandards (see ASME B46 . 1 ) and not by instruments having stylus tracers and electronic amplification.
- Raised Face Either a serrated-concentric or serrated-spiral finish having from 3 .2 µm (1 25 µin. ) to 6.3 µm (250 µin. ) average shall be furnished. The cutting tool employed should have an approximate 1 .5 mm (0.06 in. ) or larger radius, and there should be from 1 .7 to 2.2 grooves per mm (44 to 55 grooves per inch).
- Ring Joint The side wall surface of the gasket groove shall not exceed 1 .6 µm (63 μin) roughness .
The finish of contact faces of pipe flanges shall be judged by visual comparison with Ra S tandards (see ASME B46 . 1 ) and not by instruments having stylus tracers and electronic amplification.
- Raised Face Either a serrated-concentric or serrated-spiral finish having from 3 .2 µm (1 25 µin. ) to 6.3 µm (250 µin. ) average shall be furnished. The cutting tool employed should have an approximate 1 .5 mm (0.06 in. ) or larger radius, and there should be from 1 .7 to 2.2 grooves per mm (44 to 55 grooves per inch).
- Ring Joint The side wall surface of the gasket groove shall not exceed 1 .6 µm (63 μin) roughness .
Flange Tolerance
| Item | Description | Specification | Tolerance |
| Facing | Ousied Diater of Raised Face | 2.0 mm (0.06 in.) | 12≤NPS≤24 ±1.0 mm (±0.04 in) |
| NPS≥26 ±2.0 mm(±0.08 in) | |||
| 7.0 mm (0.25 in.) | 12≤NPS≤24 ±0.5 mm(±0.02 in) | ||
| NPS≥26 ±2.0 mm (±0.04 in) | |||
| Raised Face Height | All NPS | ±1.0 mm (±0.04 in.) | |
| Ring-Joint Facing | L(Depth of Groove) | +0.4 mm,-0.0 mm (+0.016 in.,-0.000 in) | |
| D(Width of Groove) | ±0.2 mm (±0.008 in.) | ||
| P(Pitch Diameter) | ±0.13 mm (±0.005 in.) | ||
| r(Groove Fillet Radius) | r≤2mm(0.8 in) | ||
| r>2mm(0.8 in) | |||
| 23°Angel | ±1/2° | ||
| Flange Thickness | NPS≤18 | +3.0 mm,-0.0 mm(+0.12 in.,-0.0 in.) | |
| NPS≥20 | +5.0 mm,-0.0 mm(+0.19 in.,-0.0 in.) | ||
| Hub Dimensions | Nominal Outside Diameter of Welding End of Welding Neck Flange |
12≤NPS≤24 | +4.0mm,-1.0 mm (+0.016 in.,-0.03 in) |
| NPS≥26 | +5.0mm,-1.5 mm (+0.21 in.,-0.06 in) | ||
| Nominal Outside Diameter of Welding End of Welding Neck Flange |
12≤NPS≤18 | ±1.5 mm (±0.06 in) | |
| NPS≥20 | +3.0mm,-1.5 mm (+0.12 in.,-0.06 in) | ||
| Overal Length through Hub on Welding Neck Flanges | 12≤NPS≤24 | +3.0mm,-5.0 mm (+0.12 in.,-0.18 in) | |
| NPS≥26 | ±5.0 mm (±0.19 in) | ||
| Driiling and Facing | Bolt Hole Diameter | +2.5mm,-0.5mm(+0.10 in.,-0.02 in) | |
| Bolt Circle Diameter | ±1.5 mm(±0.06 in) | ||
| Center to Center of Adjacent Bolt Holes | ±0.8 mm (±0.03 in) | ||
| Eccentricity between Bolt Circle Diameter and Machined Facing Diameters | 12≤NPS≤24 | 1.5 mm (0.06 in.) | |
| NPS≥26 | 2.0 mm (0.09 in.) |
Bolting
Bolting The bolting listed in Table shall be used in flanged j oints covered by this Standard Practice . Bolting produced from other materials may be used if permitted by the applicable code or governmental regulation. All bolting materials are subject to the following limitations .
High Strength Bolting Bolting materials having allowable stresses not less than those for ASTM A193 , Gr. B7 are listed as high strength in Table. These and other materials of comparable strength may be used in any flanged joint.
In termediate Strength Bolting The bolting materials listed as intermediate strength in Table, and other bolting of comparable strength, may be used in any flanged joint, provided the userverifies their ability to seat the selected gasket and maintain a sealed joint under expected operating conditions .
Low Strength Bolting Bolting materials having not more than 207 MPa (3 0 ksi) specified minimum yield strength are listed as low strength in Table. These materials and others of comparable strength shall be used only in Class 150 and Class 300 joints , and only with gaskets as described in Section 3 . 3 . 2 .
FLANGE DIMENSIONS
Dimensions are in mm except bolt holes
Class 1 50 , 19 .6 bar at Atmospheric Temperature Raised Face – SI (Metric)
Class 300 , 51 .0 bar at Atmospheric Temperature Raised Face and Ring-Type Joints– SI (Metric)
Class 400 , 68 .3 bar at Atmospheric Temperature Raised Face and Ring-Type Joints – SI (Metric)
Class 600 , 102 .1 bar at Atmospheric Temperature Raised Face and Ring-Type Joints – SI (Metric)
Class 900 , 153 .1 bar at Atmospheric Temperature Raised Face and Ring-Type Joints – SI (Metric)
