Basically a valve that a pipeline pig can pass through - i.e. the valve has a bore the same size as the pipeline that it is attached to, and without any obstructions when fully opened. Typical ones that I have seen are full bore ball valves.
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.
A critical starting point is: if the pig can penetrate the valve without damaging the trim, then that valve is considered piggable for that particular pig. There are no standards covering this issue at present.
Heather Smith Alloy valves from The Alloy Valve Stockist
Porcine's line of piggable valves includes some extraordinary features:
- bacon: a sodium and chloride based manufacturing process, derived from its colloquial origins, bake(d)-on
- ribs: valve body's internal striated, expandable FLEX® support structure
- Wurst: a thin membrane separating the valves 'guts' from the process
- pulled: opposite of a pushed pig valve
- smoked: manufacturing aging treatment designed to increase life expectancy
- pate: a pasty mixture of lubricants for pigging service
- prosciutto: conforms to the national Italian UNI standards
- Schweinebraten: DIN & NAMUR standard for harsh duty
As with all piggable valves, trichinella is destructive to the valve bodies and trim and toxic to plant personnel infected by exposure. Consult appropriate MSD's.
danw2
Now you are just taking the piss. It is hard to get people to take you seriously when you talk about pigging as it is! Great post though!
-breakfast sausage: conform to BS standard?
