Recommended for sharing: Some experiences in the design of static equipment for an EPC project in the petrochemical industry

1 Response to the owner’s technical specifications: In EPC projects, the owner is not highly involved in the specific implementation of the project; rather, they exercise control at a strategic and principled level. Their requirements regarding design, manufacturing, construction, etc., must be incorporated by the design department into the \"uniform design regulations\" to guide the actual design work. After some time had passed since the detailed design work began, the owner issued to the various design agencies a newly revised set of technical requirements for design, manufacturing, and construction. This set included a \"Technical Requirements for Equipment Design,\" which the static equipment department studied and analyzed, using it as a basis to update the \"Uniform Design Regulations.\" However, one provision in the owner’s “technical requirements” did not receive sufficient attention: it stipulated that austenitic stainless steel heads must undergo solution heat treatment. The design team considered this requirement to be a \"one-size-fits-all\" approach; it was far stricter than the current standards for heads and not economically reasonable. Therefore, it was not taken into account when updating the \"Uniform Design Regulations\", and the manufacturing of heads in the design documents was required to comply only with the current standards. Upon the arrival of the equipment, the owner conducted hardness tests on all the austenitic stainless steel end caps, using the hardness specifications specified in the raw material standards as the acceptance criteria. A few cases were found to be \"unqualified,\" and the design firm and the supplier were required to make corrections. The lesson learned from this incident is that designers should have a strong sense of commitment to fulfilling their obligations; when deviations from the owner’s relevant regulations are necessary, technical clarifications must be sought and the owner’s approval obtained. If it is felt that the owner’s requirements are unreasonable, communication should be held with the owner to understand their needs, and appropriate acceptance standards and technical requirements should be determined through negotiation. To avoid the need for corrections due to failure to pass the owner’s inspection, which could delay the project timeline.

2 Division of labor for large towers The lifting of large towers is one of the critical paths in the construction plan for the entire facility. Whether they can be delivered and installed on time has a significant impact on the proper scheduling of the use of large cranes, the necessary preparations in civil engineering, the vertical construction of the facility’s layout, as well as subsequent installation work. Furthermore, in order to minimize the costs and risks associated with secondary work at heights, large towers usually require modular lifting as a whole; they need to be equipped with their necessary components on the ground, so that the lights can be turned on once the tower is erected. In addition to the tower body, it also involves the design, procurement, and construction of the tower internals as well as the materials attached to the tower (ladders and platforms, insulation and corrosion protection measures, pipelines attached to the tower, lighting fixtures and wires, etc.). There are many professionals, departments, and organizations involved from the design stage through to the lifting phase, including the various main specialties in the design department, the procurement department, the owner, the interior components suppliers, the manufacturing plants, the transportation companies, and the lifting contractors. All parties need to work closely together, adjusting their schedules backward based on the lifting deadlines, at each stage of the process. For the static equipment discipline, the key milestones in the design process of large towers include: specifying the basic requirements, submitting the technical documents for procurement of the tower and its internal components, issuing the construction drawings for the tower, reviewing the proposals submitted by internal component suppliers regarding materials, transportation, and lifting plans, etc. Additionally, it is necessary to assist the project department in carrying out various coordination tasks. There are several issues worthy of attention in this regard. 1) The internals are designed, manufactured, and installed under the supervision of the internals supplier; those that cannot be inserted through the manhole should be taken to the manufacturer’s facility for installation before the tower is sealed ； 2) The internal component fixings are designed by the internal component supplier and supplied by the manufacturing plant; the construction drawings for these fixings shall be delivered to the manufacturing plant after design review ； 3) The ladder platform attached to the tower is designed by the static equipment specialist. It is prefabricated at a steel structure factory and then transported to the site for assembly. It is one of the key components in the “clothing and hat” process of the tower. Additionally, the installation of internal components after the tower has been hoisted into place also needs to be carried out via this ladder platform ； 4) The project is located along the coast and is close to a port. Delivery of the large tower is carried out by sea, in the form of a complete unit. The design of the transportation mounts must take into account various conditions that arise during the waterborne transport process, from the workshop to the port, through loading onto roll-on vessels, sea transport, unloading from roll-on vessels, and finally from the port to the construction site, in order to ensure safe and smooth transportation. Furthermore, the efficiency of installing the components inside the tower is also crucial for the overall progress of the project. This is especially true for large towers, which have a large number of components; prior to installation, it is necessary to carry out technical briefings, component inspections, as well as planning and organization of the construction process, in order to prevent materials and equipment from occupying the area around the tower for too long and interfering with the work of other teams.

3 The design, procurement, and construction of the storage tanks are carried out simultaneously. For the atmospheric pressure storage tanks in this project, the approach of \"designing while procuring and constructing at the same time\" is adopted: the drawings are provided in batches, materials are purchased in batches, and as soon as a batch of materials arrives, they are used for prefabrication and welding. Upon receiving the necessary requirements, the static equipment department first provides the ordering drawings to the procurement department and the construction team, which are used for ordering the main materials and pre-producing the components. Due to the progress of upstream specialized work, the ordering drawings do not include the locations of the pipe openings and ladder platforms; the specifications for the instrument ports are listed as “to be determined”. During this period, the static equipment team continued with the detailed design work—creating construction drawings—and promptly provided the assembly drawings, component drawings, and manufacturing specifications to the construction party. The orientation of the pipe outlets, as well as the placement of ladder platforms and pre-welded components, are determined after the piping work related to the pipeline discipline is essentially completed. The locations of the instrument connections are decided once the automation discipline receives the materials supplied by the vendor. The static equipment discipline issues the corresponding drawings once the necessary conditions are met, and orders the required materials; once the construction team receives all the complete construction drawings, it can proceed with the construction work on a full scale. In the preliminary stages of tank construction, design plays a leading role, with procurement and construction following up promptly. In the later stages, the focus is on ensuring smooth construction, and the needs arising during construction are met in a timely manner by the design and procurement teams. This not only shortens the project timeline but also helps maintain good quality control, demonstrating the advantages of integrated design, procurement, and construction under the EPC project model. However, there are still some areas that require improvement. 1) The design failed to play its proper role in EPC projects; it still adhered to the division of responsibilities typical of the DBB approach. Instead of providing directly a \"list of materials for pipe connections\" and \"detailed drawings for ladder platforms\", on-site construction technicians were responsible for determining these details, which was one of the indirect reasons for the purchase of some materials in insufficient quantities or in the wrong types. 2) The materials are too diverse. There are a large variety of sheet materials, pipes, and steel sections used for ladder platforms, insulation supports, pipe supports, and pads in the entire tank area; this diversity poses difficulties in procurement and usage management. Therefore, when requesting these materials, after confirmation by the design team, appropriate combinations or alternatives were used. 3) There are flaws in the drawing version control. After receiving the construction drawings, the construction contractor failed to promptly collect and seal the order drawings, resulting in a situation where the order drawings and the construction drawings coexisted, were used interchangeably, or misused. Fortunately, this was detected and corrected in a timely manner. It is recommended that in future order drawings, a note in large, bold font be placed in a prominent position indicating that \"this drawing is intended solely for material ordering and the prefabrication of tank top (wall, bottom) plates.\"

4. Design’s support for procurement activities: In EPC projects, in addition to carrying out its regular design tasks, the design department must also submit technical requests to the procurement department according to the schedule, and participate in subsequent bid evaluations, technical negotiations with suppliers, and the review of funds returned by suppliers. Among these, the preparation of technical documentation for requests and the review of suppliers’ technical documentation are primarily the responsibility of the design department. The technical request document serves as an important basis for requesting quotes for equipment or materials, obtaining supplier quotations, and concluding contracts. Its main contents include necessary explanations, requirements regarding the seller’s qualifications, applicable standards and specifications, the seller’s responsibilities for supply and work, technical requirements such as on-site natural conditions, manufacturing, inspection and acceptance, and delivery methods, requirements for documents to be submitted by the seller, performance guarantees, etc. Attachments may include drawings or equipment specifications, technical conditions or design details, as well as a list of subcontractors. From a practical perspective, the technical documentation submitted for this project is quite comprehensive. However, the \"applicable standards and specifications\" mentioned in the main text include various national standards, petrochemical standards, and chemical industry standards; as attachments, there are drawings, the owner’s procurement technical specifications, and the general technical requirements for equipment from the design department. This results in a situation where technical requirements are simply piled up together. While this approach can fully protect the interests of the buyer, it also has obvious drawbacks. For example, there were inconsistencies between them that the designers failed to fully identify; these were not standardized in the drawings or in the main body of the technical requisition documents, resulting in multiple clarifications being required later on. It is recommended to formulate specialized technical requirements for project requests based on national standards, the owner’s procurement technical specifications, and the unified regulations set by the main design institute, according to the type of equipment. The EPC general contractor enjoys a high degree of autonomy and flexibility during the project execution process. The design work for a small number of \"special equipment\" in this project is also entrusted to the suppliers, such as non-metallic equipment and self-standing steel chimneys. Engineering companies are not familiar with the design of certain “special equipment”; it is a wise approach to leave both their design and manufacturing to specialized manufacturers in related industries. The review of supplier refunds is primarily carried out based on the “List of Key Review Items”. The purpose of the review is to check the completeness of the design documents, whether they meet regulatory and mandatory standards, as well as the requirements of technical agreements. “The “List of Key Items for Review” was prepared in accordance with HG/T20701.6-2000 \"Key Points for Reviewing Drawings of Manufacturers Specializing in Containers and Heat Exchangers\", and it specifies the particular items and requirements for review, thereby enhancing the standardization of the review process and ensuring its quality.

5 Collaboration between design and manufacturing plants: Selecting appropriate suppliers, supervising the manufacturing process, and conducting proper quality checks before shipment are fundamental measures to ensure the quality of static equipment supplied. Therefore, the static equipment discipline should set appropriate requirements regarding the bidder’s qualifications and experience in the technical documentation for procurement, provide an inspection and testing plan for the buyer, and maintain good cooperation with the supplier. Design is the foundation of manufacturing, and manufacturing is the process of bringing design to life. Before manufacturing, the manufacturer should thoroughly study the design documents to understand the design requirements and identify any potential issues as early as possible. If necessary, the design team should provide technical explanations to ensure a smooth transition between design and manufacturing. Regarding the problems and difficulties that arise during the manufacturing process, the manufacturer should inform the buyer promptly and honestly, and, while ensuring safety and quality, assist in finding reasonable and compliant solutions through design. The problems that occur during the manufacturing process of the equipment for this project can be divided into two categories. One category is human errors; for example, workers may overlook or misinterpret drawings, resulting in incorrect hole drilling. In such cases, it is possible to request the design institute to modify the piping layout, or to have the incorrectly drilled holes repurposed as spare openings while having the designers designate another location for drilling new holes. The second category consists of difficulties arising from objective constraints; for example: a) the use of a substitute for a certain material due to difficulties in obtaining it in sufficient quantities, which is common with piping materials ； b) If, due to layout constraints, the pipe ends and accessories interfere with the longitudinal ring welds of the cylinder, an application can be made to adjust the position of those pipe ends and accessories ； c) Change in non-destructive testing methods: for example, when the pipe opening diameter is small and magnetization using existing equipment is difficult, MT must be replaced with PT ； Due to the large size of the equipment, which prevents it from entering the flaw detection room, or for environmental reasons, it is necessary to replace RT with recordable ultrasound or similar methods.

6 Design support for installation work: Installation is the process by which the project takes physical form; it falls within the later stages of a project. Some issues that arose during the earlier phases such as design, procurement, and foundation construction also come to light at this stage. During the installation of static equipment, issues such as interference between the equipment’s nozzles and attachments and the foundation, dimensional deviations in the equipment supports or foundation, and missing components often occur. 1) Interference: For example, if the length of the pipe outlet below the ear mount is too long, it will interfere with the beams of the structural frame during lifting, preventing the equipment from being placed in position ； The inner ring support rod in the tower skirt (used for reinforcement during transportation and lifting) interferes with the foundation boss, preventing the tower from being positioned properly, etc. Considering the difficulty of making corrections, the preferred approach is to cut off the components that cause interference with the equipment. 2) Dimensional deviations of the supports or foundation; for example, the diameter of the anchor bolts used for the equipment supports may not match that of the civil engineering foundation. This is due to significant errors in foundation construction or equipment manufacturing. If the deviation is small, it is possible to enlarge the holes in the support base plates; however, if the deviation is large, it becomes more complicated, and in some cases it is even necessary to rebuild the foundation ； Furthermore, errors in the elevation of the ear mounts, or legs that are too short or too long, can also occur from time to time. Such problems can be resolved by modifying the piping, raising the ear mounts, or lengthening or cutting the legs. 3) Missing components: For example, some pre-welded parts of the ladder platform are omitted. Currently, engineering firms use a relatively simplified drafting style for ladder platforms; they only provide assembly drawings along with standard drawings, without any part drawings or bill of materials. As a result, it’s quite common for manufacturers to overlook certain materials during the material procurement process ； The type or quantity of thermal insulation supports is incorrect, failing to meet the requirements of thermal insulation installation; this is due to the designers’ lack of understanding of the relevant installation techniques. For equipment that has undergone heat treatment and cannot be welded, the original design plan must be modified; direct repair welding is not permissible. The causes of these problems are partly due to design oversights, such as inadequate design considerations, insufficiently detailed drawings, poor communication between different teams, and lax verification of the work submitted by suppliers and subcontractors. There are also reasons related to inadequate supervision and inspection of the equipment and foundations during construction. From economic and efficiency perspectives, it is generally preferred to carry out tasks such as cutting, repairing, modifying, adding, or expanding equipment nozzles and accessories. This requires the static equipment team to overcome \"departmentalism\" and prioritize problem-solving in order to play a positive role in ensuring the efficiency and quality of equipment installation.

7 Conclusion EPC projects require that, in addition to fulfilling the usual design responsibilities, designers also need to consider the project as a whole, coordinate and integrate efforts with relevant specialties and organizations at the stages of procurement and construction, and adjust the design plans when necessary. For the static equipment discipline, it is essential to start with the owner’s requirements, carry out proper design work and coordinate with related disciplines, in order to ensure that the final design meets standards regarding reliability, safety, cost-effectiveness, and constructibility ； Secondly, the design scope must extend to procurement and construction (the on-site construction of storage tanks), and it is also closely interrelated with these processes. As the leading element, design should provide adequate technical support for procurement quality management and ensuring construction progress ； Thirdly, design is the foundation of manufacturing; manufacturing, in turn, thoroughly tests the constructability of the design. Therefore, good cooperation between designers and manufacturers is of great significance in ensuring manufacturing quality and meeting delivery schedules ； Fourth, it is also the responsibility of the static equipment specialty to actively assist in resolving problems that arise during equipment installation, thereby ensuring the efficiency and quality of the installation process. References: He Caili. Analysis of several issues regarding design management in an EPC project for the petrochemical industry. Guangzhou: South China University of Technology, 2015. Li Chongyi. Quality control and improvement during the design phase of an EPC project in the petrochemical industry. Beijing: Beijing Institute of Technology, 2016. GB/T 25198-2023 Pressure vessel heads. Liu Tong. Preparation of schedule plans for overseas chemical EPC projects. China Petroleum and Chemical Industry Standard & Quality, 2022, 42(12): 82–84. Su Shengli. A discussion on the overall management of the hoisting process for large towers in ethylene plants. Petrochemical Equipment Technology, 2022, 43(4): 51–55. Chen Kun. Design and analysis of transportation saddles for propylene towers. Engineering Technology Research, 2021, 6(01): 96–97. Wang Xiaobiao. Measures to improve the installation efficiency of ultra-large tower internals. Chemical Industry Management, 2023(06): 109–111. Li Hongtao, Tian Tao, Kong Deren, et al. Design support during the procurement phase of Aramco’s engineering projects. China Logistics & Purchasing, 2018(15): 68–69. HG/T 20701.11-2000 Format and preparation guidelines for equipment and material requisition forms and technical specifications. Song Lifeng. Management of equipment procurement and inspection in EPC projects. Project Management Techniques, 2021, 19(7): 93–96.