Definition and dimension charts of Weldolet fitting

What is Weldolet?

Weldolet fitting is one of the most common types of piping components and this is a type of Olets. This is used for take branch connection from run pipe lines to branch pipe line and connected by butt weld welding process with 90° branch connection. In weldolet both ends will be beveled, mostly used for big bore to small bore connection with high pressure services pipe connection (more than 2 inches). Weldolet fittings is used with butt weld connection fittings the same at outlet pipe also to minimize stress and to provide reinforcement for connection.Weldolet fittings schedule always use the same or higher schedule than branch run pipes for higher strength. This is available with full size or reducing size as well (Full size means the same size as run or header pipe size for example 4 inch to 4 inch branch connection And reducing size means branch size is less than run or header pipe size likes 4 inch to any size less than 4 inch).  Some common standard and code are used to select the Weldolet that is ASTM A234, MSS SP-75, ASTM A403. In some place standard TEE is also used instead of Olets, but Olets is cheaper, light weight and easy to weld. 

Weldolet picture

This is used where the branch pipe has less bore size than the header or run pipe. One other method is also used for branching the pipe connection with RF pad welding but this will be heaver and more economically. Olet are designed as per dimension Piping Code ASME B31.3. This is a type of Olets. Olet fittings (mostly called Branch Connection Fittings or Outlet Fittings) There are 12 types of Olet available in market these are as follows. Generally Sockolet is known and used as a socket fitting, and fabricated or available in Class 3000#, 6000# and 9000#.

Types of Olets

  • Weldolet 
  • Sockolet
  • Insert Weldolet
  • Elbolet 
  • Threadolet
  • Flexolet
  • Sweepolet 
  • Brazolet
  •  Coupolet 
  • Latrolet
  • Sweepolet
  • Nipolet


Schedule STD Weldolet Dimensions
Dimension chart for weldolet is given below

Schedule STD Weldolet Dimensions

Schedule XS Weldolet Dimensions
Schedule XS Weldolet Dimensions

Schedule XXS Weldolet Dimensions
Schedule XXS Weldolet Dimensions

Selection of Weldolets

During the section of Weldolet, some of the technical details are required these are as follows.

Title name with complete details specifications- cs sock olet 800x40mm cl3000 SW, nominal bore size(mm) required for both pipe like- Header or run pipe to branch pipe ( 8″X2″). Pressure class rating/ pipe schedule- Class 150, 300, 900 or more for Schedule- Sch10, 20, 40, 80 and other, What are types of olets as required – Weldolet, Sockolet or Thredolets and other depends on your requirements,Type of end connection required – bevel end, flat end or other type, material of construction   required as per your requirement like carbon steel(cs) , MS, SS or other, which dimension standard should be followed like as MSS-SP-97, which design standard need to follow as your requirement like as ASMT A105, for steam services required (IBR or NON-IBR).

Following materials code are available that is Carbon Steel (ASTM A105 for high-temperature, A350 LF2/LF3 for low-temperature), Alloy Steel (ASTM A182 Grades F5, F9, F11, F22), stainless steel (ASTM A182 F304, F316, and other SS grades), Nickel alloys (Inconel, Monel, Incoloy, etc), For dimension standard bevel ends ASME B16.9 and B16.25, Source comes from Bonney Forge (except the sizes in millimeters) and that is Weldolet® is a registered name.

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