Section 480.550 - Minimum safety standards; effect on existing vessels; application of subsequent amendments(1) Until different rules are adopted, there is adopted as the minimum safety standards for boilers and pressure vessels the published codification of standard engineering practices and formulae known as the "Boiler and Pressure Vessel Code of the American Society of Mechanical Engineers," together with the published revisions and interpretations thereof in effect as of January 1, 1969.(2) Any vessel in use on July 1, 1961, or in use on the effective date of any adoption of different rules, shall be deemed to meet the minimum safety standards so long as the same use continues and no change occurs which would reduce the safety of its operation. Provided that if the Board of Boiler Rules finds that there is a variation from the minimum safety standards which is dangerous to health or safety, it may order that all vessels having a like variation be brought into conformity with the rules created under this section, or adopted after July 1, 1961, without variation.(3) The Board of Boiler Rules shall adopt minimum safety standards for pressure piping substantially equal to the published codification of standard engineering practices and formulae known as the "Code for Pressure Piping" of the American Society of Mechanical Engineers, numbered B 31.1, B 31.3, B 31.5, B 31.7 and B 31.9 to gether with the published revisions and interpretations thereof.1961 c.485 §8; 1969 c.582 §8; 1973 c.830 §3; 1983 c.676 §9a; 1999 c.823 §1