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In Piping Plan 71 there are tapped connections for the purchaser’s use. All ports shall be plugged with plastic plugs at the time of shipment. At installation, the user shall remove all plastic plugs and all ports shall either be connected to tubing or plugged with metal plugs. Typically, this plan is used if the purchaser might use buffer gas in the future.
Piping Plan 71 is used on Arrangement 2, unpressurized dual seals, which utilize a dry containment seal and where no buffer gas is supplied but the provision to supply a buffer gas is desired. Buffer gas may be needed to sweep inner seal leakage away from the outer seal into a collection system or to dilute the leakage but is not specified.