what is piggable valve?

Piggable valves: As above, but with the addition that full-bore ballvalves and gatevalves with full opening are clearly piggable valves, but that pigging is also done in pipelines with some other variations of valves: reduced bore ballvalves, knifegate valves with slightly protuding side supports that steal a bit of the full opening- (lesser the larger the valve), and with some full-opening check valves.

There exists a fairly vast number of pig types, from plastic skin-clad where the skin may be ripped apart and the pig damaged if protuding edges in valves and too abrupt 90 degree bends (heat exchanger 2x 90 following) exists, to more robust types, with all variations in roughness brushing against the inner pipewall.

The reason for pigging may vary from cleaning of organic growth in drinking-water pipes (light cleaning)to cleaning of burnt on process residues in pipes in heat exchangers (typically sanitary treatment/heating of organic waste - requiring rough cleaning).

Conclusion: in addition to selecting a piggable valve it should be checked that the end user accepts the valve and has a pigging process with a pig that will not be damaged by the valve and vice versa: that the pig will not damage sealings and inner surface of the valves.

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