High Temperature Water Boilers - Age Limit of Existing Boilers

High Temperature Water Boilers - Age Limit of Existing Boilers 1. The age limit of any boiler of nonstandard construction, installed prior to August 6, 1975, shall be 30 years except that, after a thorough internal and external inspection, and a hydrostatic pressure test of 1 1/2 times these allowable working pressure and held for a period of at least 30 minutes, during which time no distress or leakage develops, any boiler having other than a riveted, longitudinal, lap joint may be continued in operation without reduction in working pressure. The age limit of any boiler having riveted, longitudinal, lap joints and operating at a pressure in excess of 50 psi shall be 20 years. This type of boiler, when removed from an existing setting, shall not be installed for a pressure in excess of 15 psig. A reasonable time for replacement, not to exceed one year, may be given at the discretion of the Chief Inspector. 2. The shell or drum of a boiler in which a typical "lap seam crack" is discovered along a longitudinal riveted joint for either butt or lap joints shall be permanently discontinued for use under steam pressure. By "lap seam crack" is meant the typical crack frequently found in lap joints extending parallel to the longitudinal joint and located either between or adjacent to rivet holes. 3. The age limit of boilers of standard construction, installed prior to August 6, 1975, shall be determined from the results of a thorough internal and external inspection by an authorized inspector and the application of an appropriate pressure test. Hydrostatic test pressure shall be at 1 1/2 times the allowable working pressure and maintained for 30 minutes. The boiler may be continued in service at the same working pressure provided there is no evidence of leakage or distress under these test conditions. 4. The phenomenon of brittle fracture may result from stresses imposed during hydrostatic testing below the Nil-Ductility Transition Temperature of the materials. Where such data is unavailable on site, it is suggested that the manufacturer be contacted for the recommended minimum temperature to be used during hydrostatic testing.