MEC&F Expert Engineers : HOW TO MINIMIZE WORKER ACCIDENTS DURING PIPELINE PIGGING OPERATIONS

Thursday, November 20, 2014

HOW TO MINIMIZE WORKER ACCIDENTS DURING PIPELINE PIGGING OPERATIONS

Pipeline Pigging Operations: Open to Injury – Stay Out of the Pig’s Line of Fire

Quite a few accidents have been reported over the years during pigging operations. Even as recently as yesterday we saw pigging accidents in the pipeline cleaning business. These are recurring problems and most of the time they are caused by either human error or by mechanical failure (primarily valve failure).

Here is a typical pigging accident.

Incident Description

At approximately 5:15 p.m. on November 18, 2014, during planned work related to an internal inspection project, two batch pigs were ejected under pressure from the barrel of a 14” temporary receiving trap striking and seriously injuring two workers. A contractor on site witnessed the incident and experienced symptoms of shock.

This is the eighth NEB reported pipeline pigging related injury incident since 1990. The Board is concerned as it notes that regulators are typically only aware of those pigging incidents that seriously injure or kill, since near misses are normally not reported. Prevention, awareness, personnel training and appropriate pig trap design are key.

Factors Contributing to Pipeline Pigging Incidents

· Design of receiving trap

· Method or tools used for extracting lodged pigs

· Pressure expansion of trapped gas behind sealed pig

· Leaking valves

· Plugged vents

· Hydrate formation

· Lack of training or complacency

· Lack of hazard awareness

· False sense of security and reliance only on pressure gauges

· Sour gas trapped in pig cups

Preventive Actions

· Management review of existing facility design and design specifications

· Technical analysis which considers pigging parameters such as product, operational function, constraints, pig train length and clearance between the pig and the trap inside diameter

· Hazard identification and risk assessment including management of changes

· Awareness, training and competencies of personnel

· Procedures that address normal and upset conditions