API 4F - Clause 11.10.3 Bolt Pretensioning

#1
Hi everyone

I'm new here, so please pardon me if I'm doing this wrongly.

Here's a little background about myself.
I'm Rachel, the QA Engineer for a local company in Singapore. Our company designs and fabricates steel structures, PV, piping systems for the Marine and Oil and Gas Industry. We are an API Q1, API 4F, ISO 9001 and ASME certified company. We were API certified since 2011 and we just had our surveillance audit 3 weeks back. I have no actual technical background and am just maintaining the quality management system.

During the audit, something was brought to our attention and unfortunately we were given a major NC for that. That is with regard to API 4F - Clause 11.10.3 Bolt Pretensioning. Which states "When a preload is specified by the design, bolt pretensioning shall be considered a process requiring validation. When such values are as specified in accordance with the values in AISC 335-89, process validation in accordance with the turn-of-the-nut method per AISC's Research Council on Structural Connections document "Specification for Structural Joints using ASTM A325 or A490 Bolts" is acceptable."

We fabricated a clamp sort of structure to hold down the master skid to the skid beams. We did not validate the clamps by testing because firstly, the clamps were not installed by us. It will be installed when it goes offshore. Secondly, this structure does not use fix bolts. These bolts will be removed and installed again whenever the platforms changes. Thirdly, the load required to conduct the test is just not feasible.

So my questions are,
1) How do we go about validating this process?
2) Does validation necessary mean testing? (Auditor mentioned that validation means testing)
3) Can a simulation (using computer software) be considered a form of validation method?
4) If this structure is not fixed, how do we ensure that the offshore installer will always remember to validate them before they go into operation.

We are kind of stuck here because the structure that we have finished fabricated and sent to the customer is not in operation (no bid for the platform yet). We are unable to validate this process. We cannot possibly ask our client to rig up the entire structure just for us to validate the bolt pretensioning process as it will cost us a lot of money and resources.

We really do not know how to address the correction and corrective actions for this NC.

Would anybody here be able to help me?

Much appreciation in advanced.

Regards,
Rachel
 
#2
Hi,

The easiest way close this NCR is to do a design calculation of the bolts, this will serve as a validation document. But you must also consider this as part of your validation points in your design and development plan. So you have to revise the design plan to put this process into consideration.

Hope it helps.
 

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