May 2022, Vol. 249, No. 5

Tech Notes

Preventing Hydrate Formation Problems at Storage Sites

Special to P&GJ 

In natural gas storage facilities in underground salt caverns, hydrates can easily form in the pipes, clogging them and making regular measurement of the gas pressure difficult.  

The copper ball valve enables safe and efficient operation. (Photo: Armaturenfabrik Franz, Schneider GmbH + Co. KG)

To avoid crystal accumulations, there is the possibility of heating the gas—which, until now, was a technically complex procedure.  

Depending on the composition of the gases, the threshold for the formation of hydrates is about 75 degrees F (24 degrees C). Above this temperature, such a process is unlikely. That is why the measuring points are heated.  

However, since gas pipes are thick-walled and often flanged, it is technically complex to transfer heat from the outside to the gas inside. Especially at low outdoor temperatures, this method is very inefficient and consumes considerable energy. 

In search of a more suitable method, operators of natural gas storage facilities turned to AS-Schneider. After intensive cooperation, engineers finally developed a heatable sampling probe. This consists of a copper block with an integrated shut-off ball valve. The copper tube extends into the inner wall of the transport piping.  

An electrical heating block, screwed to the body, generates heat radiation and prevents the formation of hydrates and blockages.  

The energy-efficient block regulates the temperature precisely and safely. The length of the probe can be shortened according to the wall thickness. This allows the heat to be transferred in a dosed manner across the wall or flange. 

The static gas pressure is measured precisely. The ball valve, integrated with the probe, acts as an initial shut-off between the transport and impulse lines, preventing gas from escaping.

The heatable sampling probe prevents hydrate formation in the measuring line. (Photo: Armaturenfabrik Franz, Schneider GmbH + Co. KG)

Two independent sealing systems with ball seats made of the resistant thermoplastic polytetrafluoroethylene (PTFE) and special O-rings on the spindle provide additional safety.  

The ball valve withstands pressures of up to 3,625 psi (250 bar) and is temperature-resistant up to 248 degrees F (120 degrees C). The component has special seals that prevent the ingress of dirt. The soft-seated valve is easy to operate even under high pressure. 

The antistatic design of the valve ensures explosion protection. To prevent unauthorized access, the valve handle can be locked. 

The space-saving extraction probe has already passed its baptism of fire. Numerous operators of natural gas storage facilities use it successfully—it works safely and efficiently. The integrated ball valve and the compact design by AS-Schneider allow for easy installation.

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