Pinhole leak in fuel gas pipe line fitting allows fuel gas to escape



Reference number

Incident overview

Steel elbow with pinhole leak
The 2” - 90° steel elbow with pinhole leak has been enclosed in a metal casing.

A fuel gas pipe line fitting developed a pinhole leak allowing fuel gas to escape.

Regulated industry sector

Boiler and pressure vessel system



Investigation conclusions

Site, system and components

The oil refinery fuel gas pipe line conveys high pressure fuel gas to various processes throughout the plant.  The high pressure fuel gas pipe and associated fittings are generally made of steel to withstand the high fuel gas pressure.  The pipe fittings are typical 90° elbows, couplings, tees, valves etc. that are used to join various sections of pipe together.

Failure scenario(s)

One of the fittings (2” - 90° elbow) on the fuel gas pipe developed a pinhole leak allowing fuel gas to leak to the atmosphere.

Facts and evidence

  • Refinery process operator noticed a hissing sound in the vicinity of the 90° elbow when performing his unit rounds.
  • The refinery personnel implemented a temporary leak repair by enclosing the leaking elbow. 
  • Gas leak testing was used to verify that the leak had been contained – photo attached.

Causes and contributing factors

It is likely that the cause of the pinhole leak may be due to certain components in the fuel gas that contributed to under deposit corrosion and possibly this under deposit corrosion eventually developed into a pinhole leak.


  • Injury
    • Qty injuries: None
    • Injury description: None
    • Injury rating: None
  • Damage
    • Damage description: Gas leak in pipe line fitting
    • Damage rating: None

Incident rating


Attachment Size
E 7172-693957.pdf 474.33 KB