bmoorthy
Mechanical
- May 29, 2003
- 457
Hello All
Background:
The specification states that the Weld shall not be Anodic with respect to Base material, This statement appears as the acceptance criteria under Galvanic Corrosion Test of the Pipe Procurement specification.
The Specification does not refer to the standard test method and the specification does not mention the test duration or the test solution and the tesing arrangement.
Now the queries:
1) What are the numbers of the ASTM or DNV or EN or ISO or NACE standard for testing Pipe Line Weldments to determine whether the Weld is Anodic with respect to pipe basematerial
2) Suppose the potential measured of the pipe base material is "- 0.5" and the potential of the weld is "-0.4" (I persume it is the potential that will be determined as the measure of Anodicity or Cathodicity), is the Weld Anodic with respect to Pipe.
3) Whereas the whole sub sea pipe line is protected by providing bracelet anodes, then what could be the rationale for asking such requirements in the weldment?
4) Does the international sub sea pipe line standard or codes asks for such requiremtrns when the wleds in a carbon steel sub sea pipe line are going to be welded with carbonsteel electrodes?
5) It is my opinion that the difference between the potential of the weld and the parent material is expected to be very minimal, in the order of the difference in potential between one heat of parent steel and the other heat of steel. What is the difference in potential that is considered significant from the point of view of Galvanic corrosion, that what difference in potential between 2 items will warrent CP protection of a system?
Background:
The specification states that the Weld shall not be Anodic with respect to Base material, This statement appears as the acceptance criteria under Galvanic Corrosion Test of the Pipe Procurement specification.
The Specification does not refer to the standard test method and the specification does not mention the test duration or the test solution and the tesing arrangement.
Now the queries:
1) What are the numbers of the ASTM or DNV or EN or ISO or NACE standard for testing Pipe Line Weldments to determine whether the Weld is Anodic with respect to pipe basematerial
2) Suppose the potential measured of the pipe base material is "- 0.5" and the potential of the weld is "-0.4" (I persume it is the potential that will be determined as the measure of Anodicity or Cathodicity), is the Weld Anodic with respect to Pipe.
3) Whereas the whole sub sea pipe line is protected by providing bracelet anodes, then what could be the rationale for asking such requirements in the weldment?
4) Does the international sub sea pipe line standard or codes asks for such requiremtrns when the wleds in a carbon steel sub sea pipe line are going to be welded with carbonsteel electrodes?
5) It is my opinion that the difference between the potential of the weld and the parent material is expected to be very minimal, in the order of the difference in potential between one heat of parent steel and the other heat of steel. What is the difference in potential that is considered significant from the point of view of Galvanic corrosion, that what difference in potential between 2 items will warrent CP protection of a system?
