Managing Valves in EPCM Projects

Piping systems in oil and gas projects, including the valves used, can take 20−25% of total engineering man-hours and construction work in the projects. Piping systems connect equipment and components all over plants. This article delves into the valve cycle in EPCM projects and addresses some of the challenges related to managing valves based on real industry experiences.

VALVE LIFECYCLES

For EPCM projects, the lifecycles of valves include:

Early Engineering

Valve lifecycles normally start during the early engineering phase of a project (the basic engineering or feed phase). The type of valves, as well as size, pressure class, material, end connections and other parameters, are selected through cooperation between process and valve engineers, who work with piping and instrument diagrams (P&IDs). Project documents that show valve selection, material selection and piping material specification (PMS) are used for P&ID development. Also identified on the P&ID are actuated valves and actuator types such as pneumatic, electrical and hydraulic.

Figure 1 illustrates a P&ID for a compressor station. A compressor (Tag number K-101) increases the gas pressure and reduces the volume to facilitate gas transportation in the pipe. A suction knock-out drum (Tag number V-101) on the upstream side of the compressor is a liquid-gas separator to remove liquid droplets from the gas. Liquid present in the compressor damages this equipment, and this scenario is one of the main reasons for compressor failure. Water can wash the lubricant and cause wearing of the compressor internals. The gas discharged from the compressor is hot. Thus, an after-air cooler (Tag number E-101) is used as a type of heat exchanger for cooling down the compressed gas. The P&ID shows different types of valves with a symbol like a “bow-tie” or “90-degree rotated bow tie.” Two gate valves are connected to the top and bottom of the suction knock-out drum for venting and draining. The Figure 1 P&ID also shows more gate valves, a level control valve (LV 101) as well as a pressure safety or pressure relief valve (RV-101). The size and pressure class of the valves are parts of the line numbers (e.g. B14-RF1780−6-inch).

Detail Engineering

During the detail engineering phases, P&IDs are more mature and developed. At this phase, the list of valves named as first material take-off (MTO) are normally put into an excel sheet. An MTO should contain size, pressure class, material, end connections and other special valve requirements such as bore types (full or reduced) for ball valves. General valve requirements such as factory acceptance tests (FAT), packing, preservation, documentation, etc. are provided in project specifications. The MTO plus relevant valve specifications and datasheets are sent to potential valve suppliers or manufacturers for purposes of soliciting technical and commercial quotations. At this stage (the bid phase), a series of clarifications can be done through emails and meetings between valve suppliers and the valve technical engineer/procurement buyer. The bids are analyzed both technically and commercially and given scores, and valve manufacturers are ranked. The winning manufacturer or supplier for each bid is eventually selected for the kick-off meeting, and a purchase order is signed.

Procurement

A major milestone in the procurement phase is the purchase order. Valve suppliers or manufacturers deliver their products (valves) as well as relevant valve documents such as drawings, procedures, reports and more. Engineering for valve procurement includes tasks such as receiving and reviewing the vendor documents, vendor follow-up regarding documentation and follow-up during the manufacturing and during FAT. Valves are then released to the construction yard. Some valve manufacturers’ documents such as dimensional drawings for valves and actuators may be categorized as vital interface information. The dimensional drawings are modeled in a software program such as a plant design management system (PDMS), which is similar to a 3D AutoCAD. This design software is used to make 3D models for piping and valves, equipment and structures (Figure 2).

Construction

Some valve engineering support and activities occur during the construction phase.

Chart 1 illustrates the lifecycle of valves from the early phase of engineering until construction in an engineering, procurement, construction (EPC) project.

The valve engineer, in cooperation with the valve supplier, should solve some issues related to valves during installation. For example, in Figure 3, a pneumatic-actuated wafer double-offset butterfly valve is installed in the wrong direction at the construction site. The small figure on the left and bottom side shows the direction of installation of the butterfly valve in a PDMS model. The butterfly valve and its actuator are shown in pink. The flow direction in the PDMS model is parallel to the actuator on the same side, which is incorrect. The real flow direction is on the opposite side of what the model shows. Although double-offset butterfly valves are bi-directional and tested from both sides, they have a preferred flow direction. In this case, the butterfly valve was installed wrong in the yard. The best solution would be to remove the valve and actuator from the line and rotate the valve and actuator 180 degrees, then install them in the preferred flow direction recommended by the valve supplier. If no space exists for the actuator to be rotated 180 degrees (because of clashing with a structure, for example), the solution would be to disassemble the valve from the actuator and rotate the valve 180 degrees. This should be done by the valve supplier so it triggers after technical services (ATS) charges as well as technical support from the valve supplier in coordination with the valve engineer.

CHALLENGES

Challenges are attached to each of the various phases of the EPCM. Some of them include:

Early Vendor Selection

The end user generally selects vendors from the approved vendor list, which could be limited to two or three valve suppliers or manufacturers. In fast-track projects, valve vendors may need to be selected during the early engineering stage.

Early selection of valve manufacturers during the basic or feed phase of engineering design can provide advantages such as reducing the workload associated with vendor selection that would occur in the detail engineering phase as well as presenting the possibility of using vendor documents such as dimensional drawings earlier in the process. The challenge here is that, during the vendor bid evaluation at the early engineering phase, the scope of work in terms of valve quantities and qualities is not completely clear. This is true especially for smaller valves because of the immaturity of the engineering design at the earlier phase of bid evaluation. Sometimes, a so-called “false material take-off” that covers all possible sizes, pressure classes, materials and design of the valves within the project can be prepared and sent for seeking quotations from vendors. In some cases, an analysis may be required to see different possible scope-of-work scenarios for valves including commercial and technical impacts. For example, suppose that 200 butterfly valves in one project are made of 25 chromium (Cr) super duplex or titanium in size ranges between 4−20 inches: 80% of the scope is titanium and 20% is super duplex during the bidding. However, the percentage of the valve materials can be changed to 50% titanium and 50% super duplex in the future. Vendor X proposes a very cheap price for the titanium-made valves so it can win the bid commercially on the condition that most of the valves are made of titanium. However, Vendor Y might give the cheapest offer based on the condition that half of the valves will be made of titanium in the future.

New and Multiple Manufacturers

In rare cases, valves may be purchased from vendors out of the frame agreement or the approved vendor list because the clients want fast delivery times at reduced costs. These strategies incur several risks because of factors such as unfamiliarity by the valve manufacturer as far as project specifications and client requirements. If two vendors have been selected for supplying specific valves of the same size and pressure class, dealing with two different sets of drawings and other documents is challenging. For example, suppose there are 10 manual, full-bore ball valves in a project in a 10-inch size with a pressure class of 1500 and 22 Cr duplex material. Eight of these valves were ordered initially from Vendor X inside the frame agreement in the first MTO and purchase orders. Two more are added to the project scope very late in the project because of the process engineer’s requirements. Vendor X cannot deliver the valves on a fast track so Vendor Y is approached by the project procurement team. This is not inside the client frame agreement but enables fast valve delivery with reasonable cost and acceptable technical terms. That means there will be two different sets of drawings and other documents related to the same valves in the project. The weight and dimensions of the two valves are different from the other eight valves, which affects the layout and stress analysis of the piping system. Similar manual bulk valves ordered from different manufacturers should be coded separately to trace their impacts on weight and space.

Early Purchase Order Placement

Process, piping, valve and instrument engineers are working constantly on P&IDs to reflect possible changes such as size, pressure class, material, valve safety function, etc. In fact, maturity of P&IDs at early project stages such as basic engineering or feed phases is low. Therefore, the earlier placing of purchase orders leads to more possibilities of order changes in the future. Thus, the challenge is to order the valves as soon as possible in consideration of the fact the scope of work will see the least change in the future. Early placement of purchase orders also speeds up the procurement process and assures receipt of vital vendor data for engineering. Meanwhile, changes or cancellation of the valves in a purchase order could cause high fees and cancellation costs.

Handling Several Valve Suppliers

Ordering valves in large projects is normally a divided task with several work packages created based on valve types and often sizes. Valve vendors in different parts of the world might be selected to design, procure the valve parts, manufacture and assemble, test, pack, and ship the valves. Multiple valve manufacturers or suppliers as well as sub-suppliers for forging or casting, machining, coating, etc. from different locations adds complexity to the project. Another consideration is actuator manufacturers. The actuator suppliers will make and supply the actuators to the valve manufacturers to complete assembly and test. Lack of communication and coordination between the valves and related actuation suppliers can delay the valve procurement process. Valve packages such as manual valves (including check valves) are categorized as simple packages because they don’t need actuation.

No matter the challenges, the important factor to remember is that knowing how EPCM works and what may happen provides a means to ensure a project will run the way it’s supposed to run and end users will be happy.

This article only had room for a few of the challenges in EPCM projects. Sotoodeh also addresses selecting actuator suppliers, special valve considerations, multiple locations, political considerations and more in a special online article entitled Managing Valves in EPCM Projects: More Challenges. Go to www.vma.org.

KARAN SOTOODEH is a lead/senior valve and actuator engineer for Baker Hughes, a GE Company. Reach him at karan.sotoodeh@bhge.com