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Lord Fin Tube--Bonding test for finned tube

Bonding test for finned tube

The bond strength between the fin and tube shall be tested using a tensile test.
a) The test specimen shall be a portion of a fin wrap that is 0.5 in (12.5 mm) wide.
b) A minimum of four (4) wraps around the point the test specimen is located shall be peeled off and visually inspected to verify continuous weld of sufficient width and bonding.
c) The fin shall be pulled radially from the pipe and the maximum force recorded at point of failure.
d) The tensile strength of the weld is calculated as Force / (Measured fin thickness x 0.5 in [12.5 mm]).
e) Tensile strength should exceed the values in Table 1 below.
f) Proven parameters used in the mock-up test shall be used in the actual production welding. These values shall be submitted to us.
g) The macro specimens are be retained at the Vendors facility and forwarded to usupon request.
ES-048 – Carbon Steel and Low Alloy Finning Specification
TABLE 1: Bonding Strength Requirements
1. Carbon steel fin: 40 ksi (275 MPa)
2. 409 stainless fin: 51 ksi (345 MPa)
3. 304/316 stainless fin: 51 ksi (345 MPa)
a) Client shall be advised of dates for first run inspections 15 working days before inspection is to take place.
b) Welding operator qualifications including test tube examination results if applicable shall be available at the Vendors facility for review by client.
c) Production control shall be per machine, tube diameter, material grade and fin configuration.
Finished welded tubes to be inspected as follows:
a) 100% visual on weld interruptions
b) 100% visual on bare parts such as unfinned intermediate or ends
c) Dimensional examination on 10% of production run. Examination shall be completed evenly throughout the production run.
d) The weld bond is tested on every 5th pipe by removing one wrap from the trailing end of the pipe. The fractured surface of the fin to pipe weld is visually inspected and the average width of the weld bond as seen by the white metal exposed and will be no less than the required bonded length given in Section 5.0 b). In the event the average bond width is less than required, the previous finned pipes back to the previous 5th pipe test shall be checked.

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