MSS SP 97 Weldolet threadolet Sockolet

MSS SP-97 is an industry standard for integrally reinforced forged branch outlet fittings used to create branch connections in pressure piping systems.

The standard covers forged branch outlet fittings with:

• Butt-welding ends
• Socket-welding ends
• Threaded ends
• 90° branch connections
• 45° branch connections

What Is MSS SP-97?

MSS SP-97 is a Standard Practice for integrally reinforced forged branch outlet fittings.

It establishes requirements for:

• Essential dimensions
• Materials
• Minimum strength
• Manufacturing tolerances
• Finish
• Testing
• Marking
• Branch outlet geometry

The fittings are designed to reinforce the opening made in the run pipe and provide a reliable branch connection when installed according to the applicable piping code and qualified welding procedure.

MSS SP-97 is commonly specified for branch connections where a compact forged fitting is preferred over a fabricated branch or full-size tee.

MSS SP-97 Scope

MSS SP-97 applies to integrally reinforced forged branch outlet fittings with three principal branch-end connection types:

The standard includes both:

• 90° branch outlet fittings
• 45° branch outlet fittings

The actual commercial product name may vary by manufacturer and project terminology.

Weldolet

Weldolet is the most common branch fititngs connections, it is with butt weld end to connect main run pipe (larger size) and  the branch pipe (smaller size)

The weldolet is ideal for replacing a tee on 90-degree branches with a reinforced connection that protects the branch pipe by reducing stress concentration due to its shape and size.
Its beveled ends allow an easy installation by BW welding on the previously cut main and on the branch pipe which will have an internal diameter or Schedule generally smaller or equal to the weldolet.

Weldolets are used to provide an outlet area from a larger to a smaller pipe connection point.

Threadolet dimensions are manufactured according to MSS SP 97

Sockolet

Sockolet is a branch outolet  pipe fittings with a  Socket Welding End for branch  pipe connection.The othe end welded on the run pipe or the header,

The sockolet has full size or reduced size. Full size means to take a branch of same size as the run pipe, for example, 2 inch to 2 inch. sockolet  Reducing size is when the branch size is smaller than the running pipe size, for example, 1 inche to 3 inch.

Sockolet is designed for specific conditions based on Process piping Code ASME B31.3;  MSS-SP-97 provides dimension requirements for standard 90° self-reinforced branch connection with butt, socket, and threaded end types.

Sockolet Dimemsions as below

Pressure Ratings: 3000#, 6000#

Material available:

Carbon steel: ASTM A105 Weldolet, A105N, A350LF2 weldolet,

Stainless steel:ASTM A182 F304, F304L,F316,F316L, F317L, F321, F321H, F347, F347H, F310, F44,F51,S31803, A182, F53,S32750

Line Pipe: ASTM A694 F42,F46,F52,F56,F60,F65,F70,

Alloy steel: A182 F12,F11 weldolet,F22,F5,F9,F91,ECT

Special Material: Monel, Duplex S.S, Alloy, Inconel, 904L etc

Threadolet

Threaded Outlet is a type of branch connection thread fittings used for connecting run pipes.

Threadolet dimensions are manufactured according to MSS SP 97

The thread type could be NPT,BSPT etc

Weldolet vs Sockolet vs Threadolet

MSS SP-97-2012 

Integrally Reinforced Forged Branch Outlet Fittings – Socket Welding, Threaded and Buttwelding Ends

MSS SP-97-2019 includes essential dimensions, finish, tolerances, testing, marking, material, and minimum strength requirements for 90° and 45° integrally reinforced forged branch outlet fittings of buttwelding, socket welding, and threaded types. 

Unless specified otherwise by the manufacturer, conventional integrally reinforced forged branch outlet fittings are intended for the following header by branch combinations: STD × STD, XS × XS, SCH. 160 × SCH 160, XXS × XXS, XS × 3000, SCH 160 × 6000, and XXS × 9000. When the run and branch pipes are of differing or mixed schedules, then the selection of the branch connection shall be determined by contacting the manufacturer. Such selections shall be agreed upon by purchaser and manufacturer at time of order and may involve supplemental marking requirements determined by other standards (e.g., material grade determination, other factors). See Section 1.3. Mixed schedule branch outlet fittings are unique to the design of each system, and thus outside the scope of this Standard Practice. The adequacy of the design for light, intermediate, and heavy wall branch outlet fittings may be established by mathematical analysis as contained in the applicable pressure vessel or piping codes, or by finite element analysis. 

Common Run and Branch Combinations

Typical branch outlet combinations may include:

• STD × STD
• XS × XS
• SCH 160 × SCH 160
• XXS × XXS
• XS × Class 3000
• SCH 160 × Class 6000
• XXS × higher-pressure branch configurations

For mixed run and branch schedules, fitting selection should be confirmed according to the actual piping design.

MSS SP-97 Materials

Branch outlet fittings can be manufactured from a wide range of forged materials.

Carbon Steel

• ASTM A105
• ASTM A105N
• ASTM A350 LF2

Chromium-Molybdenum Alloy Steel

• ASTM A182 F5
• ASTM A182 F9
• ASTM A182 F11
• ASTM A182 F12
• ASTM A182 F22
• ASTM A182 F91

Austenitic Stainless Steel

• ASTM A182 F304 / F304L
• ASTM A182 F316 / F316L
• ASTM A182 F321
• ASTM A182 F347

Duplex Stainless Steel

• UNS S31803
• UNS S32205

Super Duplex Stainless Steel

• UNS S32750
• UNS S32760

Nickel and Special Alloys

• Alloy 625 / UNS N06625
• Alloy 825 / UNS N08825
• Alloy C276 / UNS N10276
• Alloy 20
• 904L
• Nickel-Copper Alloys

The material specification must be suitable for both the piping system and the manufacturing requirements of the fitting.