GU-753 – NORM HSE Precautions for Pigging Operations – PDO

Routine pigging is carried out to prevent the build-up of sludge and scale in pipelines to improve flow. Pipelines may contain NORM contaminated scale and debris and therefore radiological controls are required for pigging operations. NORM contamination of the receiver and pig has occurred previously in Receiver.

Note: NORM can be found in both oil and gas pipeline systems and monitoring for NORM is required when pigging both systems. The types of radionuclides can vary as natural gas may contain Radon 222 which decays to Pb-210. It may also contain Ra-226,228 if scale from reservoir water occurs in the system. Both radionuclides require monitoring.

A key requirement is to use the PTW and conduct a NORM Radiological Survey. The results of the NORM Survey must be recorded in the NORM database and attached to the PTW. Pigging contractors must implement this system and employ trained personnel, use calibrated NORM Meter and utilize the appropriate PPE if NORM is found ≥ 0.5 μSv/hr.NORM contaminated debris ≥ 0.5 μSv/hr background may exceed the limit for unconditional free release (1 Bq/g for Ra-226,228) and must be analyzed for activity (Bq/g).

NORM contaminated debris exceeding 1 Bq/g for Ra-226,228 cannot go to the sludge farm and must be contained in a sealed drum, labeled, and taken to the NORM storage yard in Bahja. If the pig records ≥ 0.5 μSv/hr, it must be wrapped in thick polyethylene plastic or stored in a sealed drum until cleaned. Ideally, they will high pressure cleaned in a controlled box and the debris collected for proper disposal.

The objective is to define the radiological HSE precautions for pigging operations.

This procedure shall apply to all PDO and contractor personnel involved in pigging operations