ANSI/MSS SP-44-2019: Steel Pipeline Flanges

An American National Standard developed and published by the Manufacturers Standardization Society (MSS) of the Valve and Fittings Industry, Inc., MSS SP-44, which was last revised in 2016, has been revised. The current edition is ANSI/MSS SP-44-2019: Steel Pipeline Flanges.

About ANSI/MSS SP-44-2019

Pipeline creation and maintenance makes use of heavy demands and distinctive components and processes. Line pipe is uniquely characterized by high-strength, cold worked, thin-wall of the carbon steel grade, which necessitates special considerations for the welding end of the flanges. This concern was present as far back of the establishment of this standard around fifty years ago, after MSS had received continued requests for steel pipe flanges for pipeline use, particularly in sizes larger than those covered by ASME B16.5.

The ANSI/MSS SP-44-2019 standard practice covers pressure-temperature ratings, materials, dimensions, tolerances, marking, and testing for steel pipeline flanges. In accordance with the document, the welding neck type flanges are to be forged steel, while the blind flanges can be made from either forged steel or steel plate.

The pipe sizes covered by the standard, designated as the dimensionless nominal pipe size (NPS), are NPS 12 to NPS 60, in two number intervals, with dimensional and tolerance guidelines for NPS 10 and smaller being provided by reference to ASME B16.5. Please note that international standards make use of the nominal diameter “DN” system, and the corresponding values of these are listed in the document. ANSI/MSS SP-44-2019 addresses flanges of Class, 150, 300, 400, 600, or 900.

Changes to ANSI/MSS SP-44-2019

ANSI/MSS SP-44-2019, when compared with the previous, 2016 edition of the standard, was substantially revised and reformatted. As discussed in the Foreword of this Standard Practice:

“MSS members worked with a task group commissioned by API Committee on Standardization of Oilfield Equipment and Materials (CSOEM) Subcommittee 21 (Materials) to completely review and improve the Standard Practice.”

As a result of these efforts, ANSI/MSS SP-44-2019, which also incorporates the 2017 errata reissue of the standard, is distinguished by the following changes:

• The PLS2 option was added, as well as the corresponding Annex D.1 for “PSL2 Quality Requirements”
• The carbon equivalent (CE) is now calculated the same way as MSS SP-75
• Clarifications note that material is to be fully killed
• Emphasis was added to show that results from test coupons should be representative of the finished flanges
• The standard now prohibits weld repair without customer approval
• The standard now clarifies the conditions under which dual slope hubs may be certified to this Standard Practice
• Requirements for traceability and retention of records were added for the manufacturer’s quality control program
• Cosmetic requirements were established
• information to be contained on the Certified Material Test Report was detailed
• To align with external standards, references to “DN” were removed (except in Section
• 2.2) within the body and Tables and replaced with NPS

Changes to ANSI/MSS SP-44-2016 (and the 2017 Reissue)

Similarly, the 2016 revision of the ANSI/MSS SP-44-2016 standard was major, and its updates included:

• Defined chemistry limits (added a Table 1 and removed external references).
• Clarified the “lot” definition.
• Made impact testing at -50 °F mandatory for grades over F42.
• Added requirement for hardness testing.
• Clarified allowable heat treatment methods.
• Changed marking requirements.
• Added tolerances for raised face height and bolt hole diameter.
• Added requirements for Manufacturing Procedure Specification and Inspection and Test Plans.
• Added Figure 4 to illustrate test locations and orientation.
• Removed ring gasket dimensions and referenced ASME B16.20A.
• Added Supplementary Requirements SR1 through SR16.
• Updated and renumbered the reference annex.

To correct publication processing related errata, the 2017 reissue, ANSI/MSS SP-44-2016 (Reissue 2017), replaced the 2016 version of the standard. A separate errata sheet was also issued in September 2017 for insertion into the 2016 edition.

ANSI/MSS SP-44-2019: Steel Pipeline Flanges, which revises this reissue, is available on the ANSI Webstore.