By Michael S. Forsthoffer & William E. Forsthoffer

Figure: Suggested design audit activity[/caption]

Michael S. Forsthoffer &

William E. Forsthoffer

After critical machinery is properly selected during the purchase phase (Turbomachinery International, July/Aug 2016), the next phase concerns optimum design and testing. All critical machinery is custom designed and must be properly checked during the engineering, manufacturing and testing phases to assure maximum safety, reliability and on-stream time.

This phase begins with a vendor coordination meeting (VCM). The objective is to confirm that the scope of supply and design of each individual component are in accordance with the purchase order. To assure an effective VCM, the meeting must be held in the vendor’s works with an agenda that covers all aspects of machinery design and notes the vendor engineers that are required to attend from each department.

The EPC contractor machinery specialist is responsible for the agenda, but it must be reviewed by the end user and sent to the machinery vendor a minimum of two weeks prior to the meeting. It is important that this meeting be conducted during the early design phase (approximately six weeks after order placement). Any delay beyond that exposes the user to scope, design omissions and schedule delays. Be sure also that the end user is represented by an experienced machinery specialist, operator and maintenance engineer as a minimum. It is vital that detailed meeting minutes be kept by all parties, reviewed and confirmed with action points, responsible parties and due dates at the end of each day of the meeting. Depending on the amount of machinery involved, meeting duration can be two to five days and possibly longer.

Depending on the risk class, machinery complexity and component experience, design audit meetings may be required. The need for them would have been determined during the purchase phase of the machinery based on component proven experience (Figure).

A design audit is conducted by either the EPC contractor, end user or a 3rd party consultant. Regardless of who conducts the audit, the leader must have previous design experience with the type of the machinery concerned. An agenda should be sent to the vendor a minimum of one month in advance to assure the vendor is prepared and has the proper personnel involved. Design audits, like the coordination meeting, must be conducted early in the design phase so that any modifications will not affect the manufacturing schedule. Engineering design audits as well as manufacturing audits may be conducted. If a manufacturing audit is conducted, the lead must have prior manufacturing experience.

Project Success

After the coordination meeting and any design audits are completed, timely vendor document and drawing issue and review by the EPC contractor and end user assure proper design, minimizing additional costs and schedule delays. Document and drawing issue dates and maximum allowable review times must be established during the VCM.  Project success depends on strict adherence to this schedule. If the purchasing phase and VCM/design audits were conducted thoroughly, the documents and drawings should take little time to review as many of these details were already discussed.

As a concerned end user, it is your responsibility to ensure that from the beginning of the project, EPC and vendor personnel are experienced and that teamwork is emphasized. This is achieved by early review of CV’s and personal interviews. On occasion, certain individuals may not be acceptable based on their experience level and interpersonal skill characteristics.

As an additional tip: during review of documents and drawings, watch out for vendor and EPC “cut and paste” documents and drawings. It is in their interest to minimize engineering time. As a result, frequent use of previous project material may be utilized and this may not be in strict accordance with your project design requirements. Therefore, always follow up on the next issue to assure that your comments have been incorporated.

After a period of approximately 10 to 14 months depending on machinery content and vendor workload, the critical machinery is ready for the factory acceptance test (FAT).  The importance of properly conducting and witnessing this test cannot be overemphasized. FAT requirements are part of the purchase specification and should be noted on the appropriate data sheet. Specific details should be established during the VCM. Require that the FAT agenda be submitted for review a minimum of two months prior to the FAT Test Date. A review of the FAT agenda by the EPC and the end user, and a timely response to all comments/questions by the vendor is the first step to ensuring that the FAT will be conducted with minimal misunderstandings and delays.

The next step is for the EPC and end user to require a pre-test meeting the day before the FAT. A pre- test meeting agenda is issued by the EPC to the vendor at least two weeks prior to the FAT. This pre-test meeting confirms the test agenda and discusses any other items the EPC or user want to check during the test not listed in the test agenda. Vendors are generally flexible in allowing other checks as long as they are discussed in the pre-test meeting and can be justified. The last step prior to the FAT is for the EPC and end user to establish a FAT team of experienced machinery, operations and maintenance personnel who will be responsible for field installation and start up.

During the FAT, the main objective is to confirm that the design and manufacturing of the equipment is acceptable for field operations. The performance test should be carried out at 80% or more of the actual operating speed. This allows for proper mechanical checks as well under load tests, which are important especially if the mechanical test is to be performed under vacuum conditions.

It is useful during the performance test to have a member of the test team calculate performance based on operating data from vendor tests. While vendor calculations will most likely be correct, this gives the vendor a chance to verify that everything is correct as well as providing the team with instant test curves and knowledge of how to trend performance in the field. The mechanical test should confirm that mechanical components are sound at operating speed. This includes confirming vibration and axial displacement are within acceptable tolerances, and dry gas seal leakages are minimal.

Note that it should be stated during the pre-test meeting that you would like to open the dry gas seal secondary drain port (make sure this port breaks through the area of the seal at the bottom dead center of the cavity) if you have a tandem seal. There should be zero oil leaking through this port, indicating that installation and assembly were properly performed.

One final key check to be conducted during the FAT (for barrel compressors) is to utilize the job-specific bundle removal tooling when changing the rotor out to the next one for the other mechanical test. This confirms that the tooling provided with the equipment will properly work in the field. A senior maintenance representative from the end user should be present during this check to ensure he or she is aware of the proper procedure to use this tooling. Note: this tooling should not be used in the field for at least five years.

Once all of these tests are finished, all documents are to be signed by the proper parties and a report provided by the vendor in a timely manner. The vendor will generally provide rough hand-drawn curves to the team directly after the test with the proper drawn curves in the final report.

Authors: Michael S. Forsthoffer is President of Forsthoffer Associates Inc. (FAI). FAI has been providing machinery consulting to the global oil, gas and chemical industry since 1990.

William E. Forsthoffer is CEO of FAI. Further details on best practices pertaining to this article can be provided free of charge. For more information visit www.forsthofferassociates.com or contact michael@forsthofferassociates.com