Many pipeline operators do not discover that their new pipeline valves are leaking until after the pipeline has been pressurised and put into operation. Typically, the initial reaction is to make a warranty claim against the valve manufacturer – only to discover that the original manufacturer only issues warranties against manufacturing defects.

The pipeline operator is then referred to the owner’s manual supplied by the valve manufacturer where it is usually mentioned that “in the event of seat leakage, inject Sealweld #5050 into the emergency seat sealant system”.

After a call to Sealweld or local representative – Heath Pipeline Services – it is often discovered that:

• High pressure sealant injection pumps are needed;
• New valve fittings and/or adapter fittings to connect the pump may be needed;
• Maintenance staff need to be trained in how to safely service the valve in-line and under pressure; and,
• During the training program staff are taught about ‘new valve commissioning procedures’ and wonder why these were not followed and iterated before the valve seals were damaged.

Sealweld have seen this sequence of events happen on many new pipeline projects. Valves are often installed with little concern for their function or sealing ability beyond passing the high pressure hydrostatic test.

Valve precautions

Based on many years of hands-on field experiences, Sealweld has discovered that there are literally hundreds of different ways to damage a new valve.

In the case of looping or twinning a parallel pipeline, Sealweld’s work begins during the design phase. Valve field technicians travel to the existing pipeline and perform a sealing test on all existing valves to help the design team plan the best locations for cross-over valves and tie-ins based on the condition of their existing valve inventory.

On some projects consulting engineers are engaged to oversee the valve manufacturing and testing process to make sure that all company and/or industry specifications are being followed and implemented at the factory.

It is not unusual for new valves to sit in a yard, warehouse or ocean container waiting to be installed. During this storage period, bare metal surfaces inside the valve can begin to corrode and any water inside the valve can freeze in cold climates, bursting riser pipes or extruding the seal at the back of the seat ring. End covers not securely fastened can become loose, allowing sand, dirt and airborne contaminants onto critical sealing surfaces. Open valve stem extensions can become filled with water and the inside of these pipes will begin to corrode, which then becomes caught between the internal valve stops.

In some cases the ball and/or gate can be moved from its original full open position as a result of road vibration. If valves are unloaded improperly, valve fittings, stem extensions, gearboxes and/or actuators can become broken due to rough handling.

The new valve is most vulnerable during the construction and commissioning phase of its life cycle as this is the time when the most debris is in the pipeline. Extra care and attention at this critical time can extend the lifespan of the valve many times over.

After 25 years of responding to requests from valve manufacturers to provide emergency valve sealing services on new pipeline projects, Sealweld has decided that it should become more proactive and develop procedures to prevent the damage from occurring in the first place.

Over the last 15 years, these procedures have been developed and refined over thousands of kilometres of new pipelines on all makes and types of valves and actuators. These projects include numerous TransCanada pipeline projects, the Vector Pipeline in the United States, the West-East Pipeline in China and many more.

The company’s best case study example is the Alliance Pipeline in Canada/USA. Sealweld valve commissioning technicians were onsite for any valve related function throughout the entire 18 month construction period. Every valve commissioned was proven to seal perfectly at the handover and continues to seal perfectly after eight years of in-service life.