(a) Whenever doubt exists as to the safety of an existing boiler, pressure vessel, or piping system, the marine inspector may require that it be gaged or checked to determine the extent of deterioration, and if necessary for safety may require the recalculation and reduction of the maximum allowable working pressure.

(b) For the purpose of recalculating the maximum allowable working pressure of boilers, pressure vessels, or piping which have deteriorated in service, the applicable design formulas in effect at the time it was contracted for or built must be used.

(c) When existing vessels are reboilered, the mountings and attachments must be renewed in accordance with the regulations in this subchapter in effect at the time such reboilering work is contracted for. The existing steam piping must be examined. Those portions which are in good condition and comply with minimum thickness requirements in effect at the time such reboilering work is contracted for may be continued in service. The steam piping replaced must be in accordance with the regulations in this subchapter in effect for new construction.

(d) For the purpose of this section, existing equipment includes only items which have previously met all Coast Guard requirements for installation aboard a vessel certificated by the Coast Guard, including requirements for design, fabrication, testing, and inspection at the time the equipment was new.