46 CFR § 61.05-10 - Boilers in service.
(a) Each boiler, including superheater, reheater, economizer, auxiliary boiler, low-pressure heating boiler, and unfired steam boiler, must be available for examination by the marine inspector at intervals specified by Table 61.05–10, and more often if necessary, to determine that the complete unit is in a safe and satisfactory condition. When a hydrostatic test is required, the marine inspector may examine all accessible parts of the boiler while it is under pressure.
(b) The owner, master, or person in charge of the vessel shall give ample notice to the cognizant Officer in Charge, Marine Inspection, so that a marine inspector may witness the tests and make the required inspections.
(c) Firetube boilers which cannot be entered or which cannot be satisfactorily examined internally, all boilers of lap seam construction and all boilers to which extensive repairs have been made or the strength of which the marine inspector has any reason to question, shall be subjected to a hydrostatic test of 1 1/2 times the maximum allowable working pressure. All other boilers shall be subjected to a hydrostatic test of 1 1/4 times the maximum allowable working pressure.
(d) In applying hydrostatic pressure to boilers, arrangements shall be made to prevent main and auxiliary stop valves from being simultaneously subjected to the hydrostatic pressure on one side and steam pressure on the other side.
(e) If the marine inspector has reason to believe that the boiler has deteriorated to any appreciable extent under the bottom where it rests on saddles or foundations, he shall cause the boiler to be lifted to such position that it can be thoroughly examined, provided the examination cannot be made otherwise.
(f) The marine inspector may require any boiler to be drilled or gaged to determine actual thickness any time its safety is in doubt. At the first inspection for certification after a firetube or flue boiler has been installed for 10 years, it shall be gaged to determine the extent of deterioration. Thickness will be measured at or near the waterline, at the bottom and at such other places deemed necessary by the marine inspector. Examination may be by drilling or a nondestructive means acceptable to the marine inspector. Prior to the use of a nondestructive method of examination, the user shall demonstrate to the marine inspector that results having an accuracy within plus or minus 5 percent are consistently obtainable when using specimens similar to those to be examined on the boiler.
(g) If the thickness is found to be less than the original thickness upon which the maximum allowable working pressure was based, it shall be recalculated. The thickness of the thinnest measured portion shall be used in this calculation. Either the design formulas given in this subchapter or the ones in effect when the boiler was contracted for or built may normally be used in this recalculation. In no case will an increase in the pressure allowed be made.
| Firetube boiler ≥150 psi | Watertube boiler | Any firetube boiler for propulsion | Firetube boiler <150 psi | |
|---|---|---|---|---|
| Hydro Test: | ||||
| Passenger Vessel | 2.5 | 2.5 | 1 | 2.5 |
| Other Vessel | 2.5 | 5 | 1 | 5 |
| Fireside Inspection | 1 | 2.5 | 1 | 2.5 |
| Waterside Inspection | 1 | 2.5 | 1 | 2.5 |
| Boiler Safety-Valve Test | 1 | 2.5 | 1 | 1 |
| Valves Inspection | 5 | 5 | 5 | 5 |
| Studs and Bolts Inspection | 10 | 10 | 10 | 10 |
| Mountings Inspection | 10 | 10 | 10 | 10 |
| Steam Gauge Test | 2.5 | 2.5 | 2.5 | 2.5 |
| Fusible Plug Inspection | 2.5 | 2.5 | 2.5 |
1 All intervals are in years.
2 Where the 2.5-year interval is indicated: two tests or inspections must occur within any five-year period, and no more than three years may elapse between any test or inspection and its immediate predecessor.
3 Intervals for hybrid boilers are the same as for firetube boilers.