C. KALE, Consultant, Mumbai, India; and M. G. CHOUDHURY, Process Plant Engineering Consultant, Mumbai, India
The aim of any successful project is to achieve consistent trouble-free operation at the rated capacity. Based on the authors’ 40 yr of combined varied experience in petrochemical projects, certain pinch points have been identified that must be addressed early in the process to avoid delays. These points are applicable for normal “stick-built” plants and not for plants with a high degree of modularization.
Executing such an approach necessitates an awareness of safety, mechanical and process requirements.
A project is a relay race with the baton passed on from engineering to procurement to construction to operation. Every point is significant—often throughout each stage, issues are left for the later “runner” to resolve. The list of factors discussed here is certainly not exhaustive, but details points that are often disregarded.
The intent is that as the end user/operations assumes responsibility, due diligence has been accomplished each step of the way to ensure smooth and trouble-free startup and operation at rated capacity.
General observations. Receiving equipment after it has been ordered can present surprises, with some arriving early and some being delayed. A typical schedule is 18 mos–24 mos. Some equipment may arrive in 6 mos, while others can be at the very late stage of this range.
It is sensible to have packing and preservation procedures to suit. Typically, it is advisable to enumerate the storage conditions (closed or open storage, ground preparation, temperatures, humidity and rainfall, etc.) and ask for preservation to suit for about 18 mos. Generally, rotating equipment like pumps and motors may require rotation by hand and padding with an inert gas. Warehouse facilities must be tailored accordingly.
Coatings may be applied for parts for preservation, and methods and supplies for removal must be ensured. For example, a solvent may need to be circulated, requiring a designated area, temporary pumps, tanks piping, etc.
Columns and high length-to-diameter-ratio [(L/D) ratio typically > 20] equipment require numerous saddle supports (unless fabricated onsite). Should these be scrapped, returned or sold as scrap? Weight and quantity are important considerations. Do such actions invite taxes or duties?
The center of gravity (CG) of equipment is marked to ease lifting and installation. Lifting beams and lugs, specialized tools and tackle are often required. The contractor and construction team must understand and ensure that all requirements are in place for erection. Consider the use of foundation templates and dummy trays to ensure trouble-free erection.
Rotating equipment assembly and performance test at the vendor’s shop must be attended by the designated mechanical engineer responsible for the equipment.
Once installed, the complete set of systems (including equipment) may require specialized treatment and/or cleaning—often acid cleaning or solvent cleaning. Is this to be out-sourced or done in-house? What quantities of acid or solvent, and additional equipment, are required? Throughout the process, benchmarks and quality control (QC) should be carefully maintained. Waste disposal should be defined early in the process. The licensor may play an important part in defining process needs, such as dryness, oxygen content, etc. Such procedures require expertise and lab equipment that may not have been part of the original plan. Will such procedures be required in annual turnarounds or stoppages?
Experts (e.g., for rotating machinery) tend to be highly experienced. They may have worked their way up through the ranks, and their knowledge and acumen for the machinery they install and commission are extensive. Their services may be required again, so assigning a capable engineer to work with them and address any of their needs is a good solution.
This applies to licensor personnel, as well. They can also expedite startups and respond quickly, advising solutions for potential abnormalities.
Static equipment. Supply should include a 300% supply of gaskets, one complete set of bolts and recommended spares, if any. Preservation procedures for 18 mos should be executed for supply.
All equipment should be flushed, dried and padded with nitrogen by the vendor. One flange should be equipped with a 2-in. pressure gauge, and all balance flanges should be with matching blind flanges that are properly gasketed (can be matching spec flanges with a metal blind).
The vendor should supply the requirements of saddles/supports, and calculations for long/heavy equipment should be checked by a specialist group. This is also true to lifting lugs and tackle.
Rotary equipment. Before hookup, check the nozzle loading permitted by the vendor and the conformance of pipe supports.
Agree on a maintenance strategy with suppliers regarding workforce, emergency response, rates, online information and feedback/analysis by vendor experts of vibration readings data, and the history of safety issues with similar supplies on an ongoing basis.
Ensure the availability and methods of storage for spares (e.g., spare rotors) in case of emergency, as well as equipment insurance. Spare rotors, Methodology of storage for the same. Preservation procedures for 24 mos should be in place.
The plant maintenance and operations engineer should attend the final inspection and verify supply as per approved general arrangement drawing (GAD) and confirm the plant availability as per scope and GAD, as well as the methodology for lifting and lifting lugs.
The maintenance engineer should witness the completed packing and loading for dispatch. Packages/equipment may contain a large number of packages—in these cases, instructions for sequencing the opening and assembly will be required. The witnessing engineer will be responsible to supervise the unpacking and assembly. It is advisable to have a heavy lift/construction engineer to witness loading and dispatch.
The documentation of all calculations approved by a third-party inspector and/or a consultant is required (e.g., inspection records, hydrotest records). A specific person and team should be assigned for this task.
For large compressors, a rotating equipment expert is required to review these aspects, as well.
During pre-commissioning and commissioning, hydro/gas tests, isolations and the padding of hydrocarbons should be checked and agreed upon by the licensor or experienced operations and safety teams. Pneumatic testing is hazardous due to the high energy release in case of failures, so it should be avoided, when possible.
Gas line supports must be designed for hydrotests if they are to be carried out. Take inputs from reputed consultants as required, particularly with construction-related documentation.
For pumps, inter-changeability charts should be created to reduce inventories. Ensure the codification of all spare parts.
Other packages. Packages generally comprise both static and rotating equipment, and are distinguished by the special duties they perform. They can consist of special equipment supplied by a specialist vendor (e.g., compressors at the large end and dosing pumps at the other).
Packages are shipped for erection at the site. This may involve assembly that includes special tolerances clearances, cleaning methods, passivation, exotic lubricants, etc.
It is advisable to appoint owners for these packages to follow the equipment cycle from specification to commissioning. Packages are best tested after they are fully assembled at the manufacturers works and witnessed by inspection operations and maintenance personal before being dismantled and packed.
Since the number of packing units may be large, site inspectors must be present during packing to avoid assembly-related problems. Packing list preparation can ensure conformity and proper identification onsite for erection.
Lube oil piping and in-contact equipment is best procured in non-corroding material to ensure long life. Strainer sets should be specified to include a duty basket and larger mesh size basket for initial flushing.
Column internals have a large number of components per tray. Trays can be in numerous sections—each tray orientation is different. Manufacturers produce and may pack a particular section to keep all trays together. Specialized knowledge will be required to properly assemble trays.
Instances of incorrect tray orientation or assembly may not be caught in time, affecting the quality of product and production.
Checks on equipment and piping. Erection of equipment piping, etc., is carried out by the construction group, inspected by QC and handed over to operations and maintenance. Different companies follow different practices for responsibilities for erection. In some cases, commissioning is also part of the erection contractor’s scope.
Shortfalls during construction can come back to haunt plant operators during actual production. Incorrect gaskets are one such example: they can operate for some time without incident. Gaskets should be color-coded to ensure their specified service use. Similar problems can arise for bolts (e.g., short bolting or incorrect specification usage).
Do gaskets require replacement after passivation/cleaning, etc.? Do you have enough gaskets of the required specification and size? In refineries and other large facilities, equipment gaskets can be very large in size. Adequate quantity procurement, and proper packaging, storage and handling must be ensured.
Are all pipe supports properly installed? Is the piping going to malfunction because a stop is not welded? Critical areas must be thoroughly audited.
Supplies for startup. A typical process plant involves a large number of pumps and compressors. The supply of oil, flushing oils, lubrication oils and local grade equivalence must be ensured, as well as the methodology for the storage, handling and disbursal to various locations. Some oils may be extremely costly per liter and should be scheduled for supply just before commissioning.
Takeaways. This article targets stick-built hydrocarbon and chemical processing plants. While execution methodologies, specifications and work processes vary for today’s larger plants, the basic principles still apply. HP
Chandrashekhar Kale is a chemical engineer from Mahaharaja Sayajirao University of Baroda and has 40 yr of experience in EPC environments for Reliance Industries Ltd. and Adani Petrochemicals, where he served in senior positions as Project Director and Adviser. Dr. Kale works as a consultant to international companies.
MG Choudhury works as a process plant engineering consultant for large international engineering companies, helping them to troubleshoot and solve various issues throughout their facilities. He formerly worked for Reliance Engineering group (REG), Toyo Engineering India and Engineers India (EIL). He now works as a consultant to many international and national organizations.