Using a Pipetech Pig Sizing Ring

The purpose of a Pipetech Pig Sizing ring is to be able to quickly assess if your Pipetech Maintenance Pig is worn beyond its effective life.

Pipeline pigs must have an interference fit, or oversize, in order to seal and clean. Pipetech Pig Sizing rings are made to a specific ID taking into account a minimum acceptable oversize of the pig for the pipeline the pig is being used in. The label on the Pig Sizing Ring will show the pipe size and the wall thickness of the pipe that your Pipetech Pig was made for. For example a Pig Sizing Ring made for .188”/4.8mm wall thickness should not be used to check a Pig that was made for a .125”/3.2mm wall thickness pipeline.


The procedure is simple. Stand or hold the Pig with the nose facing straight upwards and rest the Pig Sizing Ring on the nose of the Pig DO NOT FORCE THE RING OVER THE PIG. The Pig Sizing Ring will sit on the nose of a Pig that still has effective oversize remaining. If the Pig Sizing Ring passes over the nose of the Pig as well as the cleaning discs (if applicable) this is showing the operator that the effective life of that Pig is gone. This is a “Go-No Go” procedure.

Inspect your Pigs and discontinue use of any Pig that is damaged, blistered, swelling, etc. Pipeline environment, pipeline condition, UV exposure, age of the Pig can cause the Pigs to become hard/rigid/brittle. This is particularly true for pigs designed for use in nonmetallic pipelines. Pigs designed for use in non-metallic pipelines may show as okay with the Pig Sizing Ring but may have adverse operational issues due to becoming rigid/hard. Keep the Pig for reference or obtain photographs before discarding the Pig so that your Pipetech advisor can look at the Pig and help to assess the possible causes of these issues.