Indiana Administrative Code › Title 675 - FIRE PREVENTION AND BUILDING SAFETY COMMISSION › Article 30 - INDIANA BOILER AND PRESSURE VESSEL RULES › Rule 11 - Existing Installations of Unfired Pressure Vessels (prior to July 1, 1953) › Section 11-2 - MAWP for nonstandard unfired pressure vessels

Current through July 10, 2024
Authority: IC 22-13-2-8
Affected: IC 22-15-6
Sec. 2.
(a) The MAWP
				for a nonstandard unfired pressure vessel, for which data is available
				evidencing it has been so designed and constructed as to be substantially
				equivalent to a standard unfired pressure vessel except for the stamping, shall
				be determined on the same basis as for a standard unfired pressure
				vessel.
(b) The maximum allowable
				working pressure for a nonstandard unfired pressure vessel not covered by
				subsection (a) shall be the least of the values found for allowable working
				pressure for any of the essential parts of the vessel (such as shell, heads, or
				nozzle openings) by the principles described in this subsection or subsection
				(c) and section 3 of this rule as adjusted for any difference in static head
				that may exist between the part considered and the top of the vessel as
				follows:
(1) For internal pressure, the
				allowable working pressure for the shell of a nonstandard cylindrical unfired
				pressure vessel such as considered in this subsection shall be determined by
				the strength of the weakest course computed from the thickness of the plate,
				the tensile strength of the plate, the efficiency of the longitudinal joint,
				the inside radius of the course, and the factor of safety. The equation shall
				be:
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Where: P = Allowable working pressure for the shell, in psig.
TS = Ultimate tensile strength of shell material in pounds
				  psi. When the tensile strength of carbon steel plate is not known, it shall be
				  taken as fifty-five thousand (55,000) psi for temperatures not exceeding seven
				  hundred (700) degrees Fahrenheit. Where the tensile strength of cast iron is
				  not known, it shall be taken to be twenty thousand (20,000) psi.
t = Minimum thickness of shell plate of weakest course, in
				  inches. When the contents of a vessel are corrosive, it shall be taken as the
				  last measured minimum thickness minus twice the thickness expected to be lost
				  by corrosion before the next inspection.
E = Efficiency of longitudinal joint depending upon
				  construction. Use values as follows:
For seamless shells
E = 100%
For riveted joints For fusion welded, forge welded,
							 or brazed joints:
E = calculated joint efficiency
For fusion single lap weld welds
E =
							 40%
For fusion double lap weld welds
E =
							 60%
For fusion single butt weld welds
E =
							 50%
For fusion double butt weld welds
E =
							 70%
For forge weld welds
E = 70%
For brazed steel joints
E = 80%
For brazed copper joints
E = 90%
R = Inside radius of weakest course of shell, in inches,
				  provided the thickness does not exceed ten percent (10%) of the radius. If the
				  thickness is over ten percent (10%) of the radius, the outer radius, in inches,
				  shall be used.
FS = Factor of safety allowed by section 3 of this
				  rule.
Note: Vessels with brazed joints shall not be operated with
				  metal temperatures in excess of four hundred six (406) degrees
				  Fahrenheit.
(2) The
				allowable working pressure for heads of a nonstandard unfired pressure vessel
				such as considered in this subsection shall be determined by the applicable
				formulas in the ASME B&PVC or API-ASME code, based on the last measured
				minimum thickness of the head in question or, in the case of heads, subject
				thickness expected to be lost by corrosion before the next inspection.
				Efficiencies for joints in a head shall be taken to be the same as specified in
				subdivision (1) for shell joints. The joint efficiencies are to be used in the
				head formulas only to the extent that the heads themselves actually contain a
				joint or joints, as distinguished from the joint between the head and shell;
				however, a determination also shall be made as to whether the strength of the
				joint between the head and shell is adequate to withstand the pressure imposed
				on the projected area of the head (namely, 3.14
				PR2), based on the least thickness of head or shell
				plate adjacent to such joint and the applicable joint efficiency specified in
				subdivision (1); and if the strength of this joint fails to meet this
				criterion, the allowable working pressure for the head (as determined by the
				applicable head formula) shall be reduced accordingly.
(3) The allowable working pressure for a
				shell course, or head, in which there is any opening larger than two (2) inch
				pipe size in the solid plate (or larger than three (3) inch pipe size if the
				net thickness of the plate, after deducting corrosion allowance, is
				three-eighths (3/8) inch or less) and that has no more reinforcement for such
				opening than that inherent in the manway or nozzle neck and its attachment
				welds, shall be taken to be sixty percent (60%) of the allowable working
				pressure computed for a seamless shell course, or head, of the same dimensions,
				using in such computations the last measured thickness of the vessel element in
				question minus twice the thickness expected to be lost by corrosion before the
				next inspection. Or, alternatively, the effect of such opening on the allowable
				working pressure for such shell course, or head, shall be computed in
				accordance with applicable provisions of the API-ASME code or Section VIII,
				Division 1 of the ASME B&PVC using the dimensions of the materials actually
				available for reinforcement of such opening after deducting corrosion allowance
				as established in this subsection.
(4) For conditions not covered in this
				subsection, applicable provisions of the API-ASME code or Section VIII Division
				1 of the ASME B&PVC shall apply.