Crack in suction header pressure gauge line results in minor ammonia leak

Location: Burnaby

Regulated industry sector: Boilers, PV & refrigeration - Refrigeration system

Impact

Injury

Qty injuries: 0

Injury description: None

Injury rating: None

Damage

Damage description: Insignificant

Damage rating: Insignificant

Incident rating: Insignificant

Incident overview

A hair line crack formed in a suction header pressure gauge line resulting in a minor leakage of ammonia.

Investigation Conclusions

Site, system and components

The suction header pressure gauge line in question was ¼ inch steel tubing which connected the ammonia suction header to the pressure gauge installed in front of the engineer’s control room so that engineer on watch can visually monitor the pressure in the ammonia suction header.

Failure scenario(s)

A section of steel tubing was damaged by corrosion leading to a crack in the tube wall and ammonia leakage.

Facts and evidence

· Photo # 1 shows a cracked and corroded suction header pressure gauge line.

· Photos # 2 and 3 show corrosion and insulation damage on the ammonia suction header.

· No evidence or records of maintenance conducted on this suction header pressure gauge line.

· The tubing was aged and no records found on site to prove any replacement or renewal of this suction header pressure gauge line.

· A ladder was required to access this tubing. The location of the tubing did not provide ready access to allow inspection to monitor its condition and for maintenance purposes. It was apparent that watch keepers did not include the inspection of this tubing in their daily routine.

Causes and contributing factors

The cause of the ammonia leak was advanced corrosion damage to steel tubing resulting in a crack in the tube wall.

It is likely that a contributing factor is this particular pressure gauge tube was not part of the daily maintenance and the deteriorating condition of this tube was not detected by maintenance personnel. Another likely contributing factor was the remote location of the tube required a ladder to access for inspection and maintenance.

Photo 1: Suction header pressure gauge line.

 

Photo #2: Ammonia suction header showing damaged insulation and visible rust corrosion

 

Photo #3: Another section of ammonia suction header showing insulation damage.