Branch Outlets: A Layman's Training Aid


Fig. 1: Pipe with a hole Fig. 2: Pipe with olet welded on

"Outlet" is a generic term for all branch type connections. They can come with threaded, socket-weld, and butt-weld end connections. The most common types are used in place of a tee. A hole is cut in the side of the pipe, the outlet is welded in place over the hole and then the additional length of pipe is attached to the outlet.



Fig. 3: Branch outlet welded to pipe

Similar to reducing tees, outlets are usually described by two sizes. The Run or Header size refers to the pipe on which the outlet is mounted. The Outlet or Branch size refers to the length of pipe branching off of the run.
Fig. 4: Branch outlet teminology

This type of fitting is contoured to match the curve on the Header Pipe and beveled on the Branch side to mate up with a beveled piece of the branch pipe.

Fig. 5: Other types

In addition, various other types of outlets are available such as: 45 degree lateral outlets which branch out on a 45 degree angle, elbow outlets which sit on the radius of a 90 degree elbow and nipple outlets which combine a nipple length (usually 3 1/2" long) with an outlet.

Potential Dangers of Material Mixes

What are the chances of a material mix?
The following statistics are factual and current -
Fig. 1: Welder
  1. A Gulf Coast petrochemical plant found,
    • Wrong electrodes used on 72 welds of pipe
    • Carbon Steel drain valves installed on alloy pipe
    • Alloy steel heat exchanger had carbon steel flanges stamped with an Alloy grade
  2. A West Coast Ammonia plant found,
    • 5,480 items for installation (1.8% of the total) were of the wrong grade of material
    • An additional 2,750 roof hangers were of the wrong alloy grade
A Purchasing/Sales Order Entry Disaster:
Carbon Steel is supplied, because the Purchase Order showed someone's hand writing as CS instead of C5 which is a 5% Cr ; 1-1/2 % Mo ; 1 % W
OR
Carbon Steel is supplied, because the Purchase Order showed someone's hand writing as FS instead of F5 which is a 5% Cr ; 1/2% Mo
Fig 2. Refinery 1
Carbon Steel Valve Substitution (1993)
Accident:
Major line break and refinery downtime
Cause:
A carbon steel valve painted with Aluminum paint was installed instead of Stainless Steel
Result:
The valve corroded within a few days of use. The valve split causing a hazarous chemical spill in the processing plant
Fig 3. Refinery Explosion

The previous accidents were factual and showed the catastrophic failure which can occur when the wrong material was installed.

We are all at fault

  • It was ordered wrong!
  • It was manufactured wrong!
  • It was labeled wrong!
  • It was shipped wrong!
  • It was installed wrong!


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