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A stub end is a type of pipe fitting used in various industrial applications to connect pipes or flanges.
It is designed to be welded to the pipe or lap joint flange, providing a secure and leak-proof joint. The stub end itself does not have any threading; instead, it acts as a sleeve that slips over the pipe or lap joint flange. This unique design allows for easy and quick disassembly of the joint when needed.
Ukuran :
1/2” -24”(DN15-DN500)Standar :
GB/T12459, GB/T13401, SH3408, SH3409; ASMEIANSIB16.9, B16.28, ASTMA403, MSS SP-43; DIN 2605, DIN2609, DIN2615, DIN2616; JSB2311,JIS B2312,JIS B2313Bahan :
Nickel Alloy, Duplex Steel, Stainless SteelLong Stub End
Stub ends are essential components used in various industrial applications, particularly in piping systems.
Simple Preparation: They don't necessitate perfectly flat or parallel cut faces.
Versatile Metal Pairing: They can join dissimilar metals, like aluminum and copper.
Thickness Adaptability: They accommodate varying thicknesses, with thinner pieces welded atop, enabling connections even with diaphragms and foils.
Stub ends are manufactured in three different types and two standard length.
Type “A”: this type is produced and machined to fit lap joint flanges.The mating surfaces of the stub end and the lap joint flange have a matching profile and surface. The lap thickness of type A stub ends is > = the minimum wall thickness of the connected pipe. The outside the stub end and the lap joint flange have a matching profile and surface. The lap thickness of type A stub ends is > = the minimum wall thickness of the connected pipe. The outside corner of type A has a radius to accommodate the lap join flange, whereas the inside corner is squared.
Type “B”: this type of stub ends is suited for standard slip-on flanges acting as lap-joint flanges. The lap thickness of type B stub ends is >= the minimum WT of the connecting pipe. The lap of these type of stub ends has generally a serrated face. To ensure tight joints, chamfers on the ID side of the flange are required.
Type “C”: this last type can be used both with lap joint and slip-on backing flanges and are fabricated out of pipes. The lap of C-type stub ends is flared over and the lap thickness is 75% of the connecting pipe WT. Type C has a short fillet outer radius able to host any back up flange.
Type “CS”: this type is similar to “C” with the difference that the lap face has concentric serrations machined during the manufacturing process.
Standard | Specification |
---|---|
ASTM A234 | Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Moderate and High Temperature Service |
ASTM A420 | Standard Specification for Piping Fittings of Wrought Carbon Steel and Alloy Steel for Low-Temperature Service |
ASTM A234 WPB | ASTM A234 is Standard Specification for steel pipe fittings includes carbon and alloy steel material for moderate and high temperature services. WPB is one of the steel grade in this standard |
ASME B16.9 | ASME B16.9 Standard covers overall dimensions, tolerances,ratings, testing, and markings for factory-made wrought buttwelding fittings in sizes NPS 1⁄2 through NPS 48 (DN 15 through DN 1200). |
ASME B16.28 | ASME B16.28 Standard covers ratings, overall dimensions, testing, tolerances, and markings for wrought carbon and alloy steel buttwelding short radius elbows and returns. |
MSS SP-97 | MSS SP-97 Standard Practice covers essential dimensions, finish, tolerances, testing, marking, material, and minimum strength requirements for 90 degree integrally reinforced forged branch outlet fittings of buttwelding, socket welding, and threaded types. |
ASTM A403 | Standard Specification for Wrought Austenitic Stainless Steel Piping Fittings. |
Benefits
Generally, the lap joint flange is of a lower grade than the material of the stub end and the pipework, thus saving the total weight of high-grade material used for the flanged joint.
The “loose” Flange concept of a Lap Joint, is very beneficial during field installation of piping systems. If two spools are to be mated up in the field, having one Flange that can be rotated is very advantageous when aligning the bolt holes, prior to the introduction of the Stub bolt and the accompanying nuts. The facility of easier orientation and alignment of bolt holes, is of particular use it there is a spool that has to be removed frequently, if positive isolation is a process requirement.
Why use Stub Ends?
Using a stud end and a lap joint flange provides an alternative method for creating a flanged connection, different from welding neck flanges.
The components involved are:
Stub End: This is akin to a pipe segment, with one end flared outward and the other prepped for welding to a pipe of the same bore size (NPS = nominal pipe size), material, and wall thickness. Flaring machines are commonly employed to shape the pipe end and then trim it to the desired length.
Lap Joint Flange: This flange type facilitates bolting the two pipe segments together, creating a secure connection.
This approach offers flexibility and ease of assembly, making it a valuable alternative to traditional welding neck flanges.