Design Calcs Sample - Audit Vessel
File: PVE-5918
Last Updated: April 5, 2012
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The ASME Audit
PVEng has been involved in many client ASME Audits, mostly for VIII-1. This sample shows the most common audit vessel, known in slang as a "Hartford Submarine" in honor of the Hartford Steam Boiler Inspection and Insurance Co. This is the type of vessel a shop builds when it has no vessels on order that it can use for an audit, or when it is first seeking ASME certification. Useful information about what is recommended for an audit can be found in:
ASME Boiler & Pressure Vessel Accreditation Guide For ASME Review Teams For Review Of Applicants For ASME Certificates Of Authorization (A, M, PP, S, E, V, HV, H, HLW, H (Cast Iron/Cast Aluminum), UD, UV, UV3, U, UM, U2, U3, RP, T, TD, TV) (guide)
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From this document:
- A Review must cover a QC Manual and its implementation.
- It is expected that fabrication functions be demonstrated using typical Code work. However they may be demonstrated using current work, a mock-up, or a combination of the two.
The above document also answers an often asked question - how do I demonstrate for more than one ASME stamp? Answer: Only one demonstration vessel is required, however more than one calculation set might be necessary:
For Applicants requesting multiple stamps, it is not necessary to have a demonstration item with design calculations for each Code Section. An item fabricated to any one of the requested Code Symbols may be used as the demonstration item. However, if the demonstration item is not to the most stringent Code requirements, the Applicant must provide additional calculations or another documentation package that contains Code calculations to the most stringent Code requirements and administrative documentation to sufficiently demonstrate compliance with all aspects of the company's QCS.
This Audit Vessel
This vessel qualifies as a mock-up. The vessel, calculation set and drawings are simple. The materials are easy to source. The fabrication is easy. And the audit team has seen it before. However, we suggest that where practical, a real in-production vessel be used instead. If a mock-up is required, we can also design other vessel configurations that would be useful after the audit - such as vertical air receivers.
We can update the drawing and calculation set to the latest code and addenda if you want to use this vessel. (Do not use these out of date calculations for an audit!) We can also re-design the vessel changing size, materials, thicknesses and nozzle configurations as desired. Also commonly requested - update the design to demonstrate radiography.
Design Calcs
This vessel is calculated using the Design Calcs pressure vessel code calculation program. This is our favourite program for ASME audits. The printout is concise, easily readable and illustrated. Design Calcs provides the easiest to understand design report of any of the commercial code calculators. If requested, we can instead provide the calculations in the other code software we regularly use: Compress, PV Elite or our own in-house Excel spreadsheets.
Calculation Validation
From the above referenced ASME document:
If computer calculations are to be used, the Applicant shall demonstrate that the computer program has the capability of producing acceptable calculations.
We have not found a consensus on what is required to validate a program to the satisfaction of the audit review team. Over the many audits we have used any of the following:
- Re-calculating the complete calculation set using hand calculations that show the same result
- Re-running the calculation set using another computer program that shows the same result
- Re-running the calculation set using computer spreadsheets that shows the same result
- Re-running the calculation set using computer spreadsheets that provide the same result and providing hand calculation validation of the spreadsheets
- Providing a letter from the software vendor stating that the software release has been reviewed and is acceptable
- Providing no validation set at all, sometimes the validation is not desired
In our experience, recalculating the original code set with another code program is the most commonly accepted method of proving that the software is producing acceptable results.
SolidWorks
The drawing is created in SolidWorks. By default, we use SolidWorks to create vessel drawings unless AutoCAD is specified. The drawing provides all required information to order material and fabricate without referring to the calculation set - a standard in pressure vessel drawings. Solid modelling is a very useful tool in the design of vessels and other pressurized equipment.
Looking for Help?
Call us if you are looking for assistance on your next audit. We can provide a quote on the drawings, calculations and verification set. Sorry, we do not provide assistance in writing and implementing QC manuals.
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