Industrial Fire Familiarization: Pipe Fittings


Industrial Fire Familiarization: Pipe Fittings


As industrial fire professionals, it is important for us to understand our process we protect.  One of the most common ways to transport materials in our plants and refineries, is through sometimes elaborate systems of piping.   Pipe itself can be made of many different materials.  Some of them being common fiberglass or PVC, to exotic metals such as hastelloy or monel.  While the make up of our pipe may change from service to service, one thing remains the same; the way we connect pipe.  An understanding of the different pipe connections will help us spot and pre plan these high frequency, potential leak sources before they become an issue.


Welded connections

Simply put, welding is the act of joining pieces of metal by heating the surfaces, and uniting them. For more technical information on welding, check out this link.


This creates a virtually seamless looking pipe spool. Under normal circumstances, as quality control, the welds are inspected visually and sometimes by x-ray to look for thin spots or cracks. If a pipe is improperly supported or experiences radical temperature changes, it is possible for a weld to crack and for leaks to develop.

Screwed connections

Our second type of pipe connection is the more basic screwed fitting.  Pipe ends are threaded to be able to fit other fittings like couplings, elbows, or valves.


Threads can become damaged before being joined by dirt, or tools coming in contact with them. Damage to the threads eventually leads to a bad connection and fluid or materials seeping by or eroding more threads until a leak occurs.


Flanged connections

Flanges are two flat surfaces that are joined together, typically with a gasket between them, and held in place by nuts and bolts. Gasket material will change according to the material being moved through the line.  Coincidentally, flanges can be either screwed or welded on, but let’s not get crazy here, stay the course.  Pictured below are pipe flanges bolted together.IMG_0263

While flange fires are the most commonly trained upon, a leak from either of these fittings would involve the same tactics.



Use these examples, and these basic facts as a tool while you are out around your facility.  A better understanding of these fittings will give you the upper hand when the alarm goes off.

For other piping related articles, check out our article on furnace tube rupture.