• structured-packing sheet thickness.
Structured-packing thickness is a major cost factor but also can be very important to constructability. To trim bid prices, vendors sometimes quote material as thin as 0.005 or 0.004 inches. This can be an issue for larger columns where workers go inside during installation. Crushing of such thin packing can be disastrous to performance. Yet, installers may cover crushed packing before it is detected. So, the risk of crushing must be recognized and addressed in the work process. Controls include time-consuming crimp straightening measures or requirements that workers stand on plywood sheets. For critical path work, the added installation time due to such controls may cost more than the price of thicker packing material. Some operating companies do not accept sheet thicknesses less than 0.006 inches if installers will work on top of the packing, and some require even thicker material for high-capacity (large crimp) structured packing.
Exceptions and clarifications. If you included a set of engineering specifications in your RFQ, a vendor may take exception in its bid to some of the requirements. Be sure to determine the acceptability of all exceptions and request bid addenda, as necessary, to comply with non-negotiable specifications.
Ascertain exactly what equipment is being offered. For example, a vendor may list a support grid for a packed bed but may depict several types of such grids in its literature. Do not assume that any particular item or model of equipment will be provided unless it is specifically spelled out in the bid text or scope of supply. If there are any questions at all, ask for clarifications!
Process guarantees. If such guarantees are necessary, be sure they are included in the bid along with acceptance criteria that details what must be done or shown to activate each guarantee.
It is not uncommon to award different towers in a multi-tower revamp to different vendors. Occasionally, even different sections of a particular tower go to different suppliers. In such circumstances and others, vendors may not offer guarantees. This may make project managers uncomfortable, but is there much real benefit to process guarantees?
Consider the value of a process guarantee for a given distillation tower. If one or more separation objectives are not met, the vendor generally must supply a different internals configuration to fix the problem. Installation costs may or may not be included, but consequential damages are nearly always excluded from process guarantees. This latter point is key: economic losses from lost production, especially from a second unplanned shutdown, generally total many times the value of a process guarantee. In addition, there may be a period where the vendor attempts to fend off process guarantee claims, citing deficiencies or inconsistencies in operating data, flaws in the design simulation, feedstock differences from design, under-designed tower ancillaries, improper internals installation or even damage from operator error. Simply demonstrating that internals are the root cause of the problem may be a daunting task, with the plant losing money all the while. Considering all of the facets of this situation, process guarantees on tower internals can be nearly worthless to the plant owner. The real objective of the process engineer is to determine that the chosen internals will work so there is no need to resort to process guarantees.
Schedule issues. When negotiating delivery schedules, it often is useful to ask the vendor for an assessment of its projected shop loads. Because tower internal revamps require a shutdown, some project managers give a fictitious shutdown date of about a month earlier than actually planned to ensure that the vendor does not bump the job for other, possibly higher margin orders.
If on-time delivery is crucial, as it can be, for example, in projects where tower work is on the critical path, you may wish to negotiate incentive/penalty clauses on approval drawing receipt in addition to finished internals shipping. Most vendors state that the main bottleneck in the design/approval/procurement/fabrication cycle occurs in the engineering design phase. By adding such clauses to the approval drawing process, project teams usually can expedite this limiting step.
Make sure the proposed time allotted for client approval of drawings is reasonable. For simple orders such as a single new tray design, a day or two may suffice to review drawings, transmit comments and have changes incorporated. For complex, multi-tower revamps, at least two weeks should be provided for the return of comments; there also should be allowance for follow-up review of modified drawings without impacting shipping schedules. This should be negotiated during the bid phase.
It can be useful to assess a vendor’s responsiveness and willingness to accommodate changes or unusual requirements. However, initial impressions can be misleading because internals vendors often have separate sales and project execution staffs; implied cooperativeness may not survive the handoff between these groups. One tactic is to ask the vendor to name the lead execution person or project manager in the bid and start a dialog with that person before the bid is accepted.
Material shortages and surcharges. Steel now is in short supply, particularly in the United States. This has caused uncertainty in both the price of raw materials and their availability for fabrication. Some internals vendors have responded with materials surcharge clauses in their bids, with the contract price subject to adjustment based on steel cost at the time of order. Other vendors may still offer firm quotes, especially for small orders for which sufficient inventory of raw materials is in stock. In cases where a surcharge clause has been included in a bid, check to see if any competing bid offers a firm price. If other factors make it desirable to pursue a bid that contains a surcharge clause, try to negotiate with the vendor to have all raw materials purchased upon acceptance of the bid (or receipt of the first payment) rather than letting surcharges accumulate on an ongoing basis.
John G. Kunesh is a part-time consultant on distillation, based in Red River, New Mexico. He served as technical director of Fractionation Research, Inc., Stillwater, Okla., until his recent retirement. E-mail him at JGKunesh@aol.com.
Raymond M. Sowiak is a senior process engineering specialist at Sunoco, Inc., Philadelphia. He is Sunoco’s technical representative to FRI and is a member of FRI’s Design Practices Committee. E-mail him at firstname.lastname@example.org.