An operation certificate issued pursuant to § 34-29A-39 is valid for not more than fourteen months from its date in the case of power boilers and high pressure, high temperature water boilers and twenty - six months in the case of heating boilers and hot water supply boilers. In the case of those boilers covered by subdivisions 34-29A-26(1), (2), and (3), for which the chief inspector has established or extended the operating period between required inspections, the certificate is valid for a period not more than two months beyond the period set by the chief inspector. Source: SL 1973, ch 229 , § 15; SL 1978, ch 257 , § 5; SL 1982, ch 18 , § 64.