Objective 02: Proof Test Flashcards
What is another name for Proof Test?
Hydrostatic Deformation Test
What type of method does the Proof Test use?
Experience-Based Method
What is the purpose of the Proof Test?
To establish a safe design pressure for components for which no rules are given or when strength cannot be calculated with a satisfactory assurance of accuracy
What is the procedure for the Proof Test?
- A full-size prototype of the pressure part is subjected to a slowly increasing hydrostatic pressure until yielding or bursting occurs (depending on the test)
- A MAWP is then establised by an appropriate formula which includes the strength of the material and a suitable safety factor
When is a burst test allowed to be stopped before actual bursting?
When the test pressure justifies the desired pressure
If a tested component underwent a burst test without bursting, can that same component be used for Code Construction?
No, because it was on the verge of failure
When can Proof Testing not be used?
When ASME Section I has design rules for the component and, in practice, such testing is seldom employed
When is Proof Testing particularly useful?
For establishing an acceptable design pressure for unusual designs, odd shapes, or special features that are difficult and costly to anaylse, even with the latest computer-based methods
Who should witness and approve the tests used to establish MAWP?
- Manufacturer’s designated person
2. An Authorized Inspector
What happens to the result of the Proof Test?
It becomes a permanent reference to justify the design of such parts if the manufacturer wants to use that design again for other boilers
How is a vessel prepared for Proof Testing?
- Outer surface is thoroughly cleaned
2. Brittle coating is applied to the entire surface
What is the purpose of the coating applied to a vessel undergoing the Proof Test?
To indicate any displacement (movement) in the vessel surface caused by the internal hydrostatic pressure by the coating flaking off wherever displacement occurs
How is Average Yield Strength determined from the Proof Test?
After test completion, 3 specimens are cut from the tested part. The average yield strength is taken from these 3 specimens.
What gauges are used on a water heater for Proof Testing?
- Hydrostatic Pressure Indicating Gauge connected directly onto the water heater
- An additional gauge is furnished if the Indicating Gauge is not clearly visible to the Operator
- Recording Gauge is installed for larger water heaters
What is the dial range used for an Indicating Gauge for the Proof Test?
1.5 times the intended maximum test pressure
