Odd Bolting ASME Code Jurisdiction Question
Odd Bolting ASME Code Jurisdiction Question
(OP)
I'm looking at an elliptical manway application in a pressurized tank, which is IAW Section VIII, Div. 1, and as part of the assembly there are bolts that are used to tighten the manway cover to the ring and seat it on the gasket. My question is whether the bolts, which are outside of the manway, fall under the jurisdiction of the code and hence must be a code bolt material and have code allowable stresses. The bolts are used primarily to position the manway as well as acheive an initial gasket seating load until the internal pressure takes over and pushes the manway onto the ring enough to seat the gasket on its own. There is some negative pressure considerations for the case where the unit trips and the tanks drain into the condenser.
Its an odd sort of case because the pressure relieves the bolts rather than trying to pull on them further and at working pressure the pressure itself is responsible for maintaining the pressure boundary on the gasket not the bolts.
Any help would be greatly appreciated so I can sort out what the real allowable stress will be in those bolts. Thanks.
Its an odd sort of case because the pressure relieves the bolts rather than trying to pull on them further and at working pressure the pressure itself is responsible for maintaining the pressure boundary on the gasket not the bolts.
Any help would be greatly appreciated so I can sort out what the real allowable stress will be in those bolts. Thanks.





RE: Odd Bolting ASME Code Jurisdiction Question
Interpretation: VIII-1-95-66
Subject: Section VIII, Division 1 (1992 Edition, 1994 Addenda); Manway Assemblies
Date Issued: June 19, 1995
File: BC95-067
Question (1): A vessel is to be built and Code Symbol stamped for Internal Pressure and Full Vacuum. The Manufacturer intends to use an elliptical manway assembly consisting of an elliptical pressed steel cover, elliptical ring, bolting and clamping bars, all supplied as standard parts by another Manufacturer, under the provisions of UG-11. If the clamping bars and bolting are subjected to stress induced by the internal or external pressure, are they considered to be pressure parts?
Reply (1): Yes.
Question (2): If Reply (1) is yes, must the clamping bars and bolting be in conformance with UG-4?
Reply (2): Yes.
Question (3): May the vessel Manufacturer discard the clamping bars and bolting supplied by the manway Manufacturer and substitute other materials which conform to UG-4 for these parts if the vessel Manufacturer can show by calculations or proof test (UG-101) that the design configuration meets all Code requirements?
Reply (3): Yes.
Also read UG-46(j) which is considered by the manway Manufacturer.
UG-46(j) Manholes of the type in which the internal pressure
forces the cover plate against a flat gasket shall have a
minimum gasket bearing width of 11⁄16 in. (17 mm).
Thus, design stress of the bolting would be based on the vaccuum condition since the bolts are only holding the manway in place at other than a vacuum condition.
This should also be considered by the vessel designer if purchasing UG-11 (Manufacturer's Standard) parts for vacuum conditions.
RE: Odd Bolting ASME Code Jurisdiction Question
RE: Odd Bolting ASME Code Jurisdiction Question
Of course I'm not considering what you mention as negative pressure that requires consideration based on the value of negative pressure and on the function requested to the bolts during the event.
prex
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RE: Odd Bolting ASME Code Jurisdiction Question
RE: Odd Bolting ASME Code Jurisdiction Question
Although I agree w/jte's position and consider the bolting as Code components, there are interpretations in Section IV and Section I that support prex's approach.
Additionally, I do not believe all UG-11 Manufacturers' identify the bolting by ASME Specification. From perusing the available literature of one specific manufacturer, the only items identified to be in accordance with ASME Code material specifications are the formed plates and rings(and of course welding to Section IX). Their design was by proof test also.
I am confident the proof test documentation would provide the bolt spec if an inquiry were to be made.