Olets offer an alternate means of connecting into the main run and do not require reinforcement. Olets are pre-shaped to the curvature of the run pipe. Flat based weldolets are available for connecting to pipe caps and vessel heads.
Olets are generally used for branching on high pressure and high temperature applications. Maximum allowable pressure of a fitting is same as for connected straight seamless run pipe of equivalent material.
Available Olet Fittings are :
1. Weldolet: Used for 90 degree branch on pipe and for branch size of 2″ and higher where socket welding fittings are used for pipe sizes upto 1 1/2″.
2. Elbolet: These are used to tap on Elbow to save space. Useful to attach thermowells.
3. Sockolet: Sockolets are used to connect small bore socketwelding piping to larger size Buttwelding Piping Header.
4. Threadolet: Threadolets are used to connect small bore threaded fittings to Buttwelding Piping Network.
5. Sweepolet: Sweepolets are primarily developed for high-yield pipe used in oil and gas transmission lines. Sweepolets provides good flow pattern, and optimum stress distribution. Sweepolet is a contoured, integrally reinforced, butt-weld branch connection with a low stress intensification factor for low stresses and long fatigue life. The attachment weld is easily examined by radiography, ultrasound and other standard non-destructive techniques. They are manufactured to meet specific reinforcement requirements.
6. Nipolet: These are used to directly attach drain valves, pressure instruments etc. to header. It helps save extra fittings and installation work.
Major dimensional standard used is :
MSS-SP-97 : Integrally Reinforced Forged Branch Outlet Fittings – Socket Welding, Threaded, and Buttwelding Ends.
Fittings Classes as per this standard are :
- Standard : Buttwelding : 1/8″ to 24″, for connecting STD thk Pipe.
- Extra Strong : Buttwelding : 1/8″ to 24″ for connecting Extra Strong Pipe
- Schedule 160 : Buttwelding : 1/2″ to 6″ : for connecting Schedule 160 Pipe
- 3000 : Threaded and Socket Welding : 1/8″ to 4″ : for connecting Extra Strong Pipe
- 6000 : Threaded and Socket Welding : 1/2″ to 2″ : for connecting Sch 160 Pipe.
Materials of Construction
These fittings are forged fittings. So they are made from the same materials as Flanges and Socket Weld Fittings.
- A105 : Standard Specification for Carbon Steel Forgings for Piping Applications.
- A181 : Standard Specification for Carbon Steel Forgings, for General-Purpose Piping.
- A182 : Standard Specification for Forged or Rolled Alloy and Stainless Steel Pipe Flanges, Forged Fittings, and Valves and Parts for High-Temperature Service.
- A350 : Standard Specification for Carbon and Low-Alloy Steel Forgings, Requiring Notch Toughness Testing for Piping Components.