By Timothy M. Ivory, PPD I
Six Ways Brownfield Piping Design is Key to Your Plant Upgrade’s Success
“Brownfield” work refers to work performed within or in addition to an existing facility. This type of work can be challenging, as the designers must contend with, work around and connect to existing equipment and piping systems. Some of the equipment and piping systems may not have been built and installed according to the original engineering documentation and as-built drawings may not have been made due to budget or time constraints.
Piping designers become very familiar with piping layout. But the one item to focus on is the path that pipe travels to its destination; whether it is 5 feet or 5000 feet. This article is going to cover 5 steps towards making a piping design project successful for your company. This is a shortened version of the entire process in the design phase of a project.
1. MEET WITH ENGINEER
Meet with the mechanical/process engineer to become familiar with the process. You will need fluid design flow, temperature, and operating pressures. Piping is a major cost in the design and construction of a fluid processing facility. Proper planning and execution of the design and routing of pipe can have a major impact on controlling the total cost. Gather all mechanical flow sheets (P&IDs) in this step.
2. FIELD VISIT (SCOPE)
Visiting the plant will give you a better understanding of how the pipe needs to be routed and any requirements you may come across (i.e. will the pipe need supports/are valves easily accessible for operators). With recent changes at our facility we’ve implemented front-end loading (FEL) or front-end engineering processes which focuses on technical requirements and identifying main costs for a proposed project. It is used to establish a price for the execution phase of the project and evaluate potential risks. It is typically followed by Detailed Design. The amount of time invested in Front-End Engineering is higher than a traditional quote, because project specifications are thoroughly extracted and the following typically developed in detail:
1. Project Organization Chart
2. Project Scope
a) Defined mechanical and chemical engineering o Safety & Ergonomic studies
b) 2D studies/layouts & 3D preliminary models
c) Equipment layout and installation plan
d) Engineering design package development
e) Process Flow Diagrams
f) Project Timeline
The engineer will go over the design pressure for piping and it shall be consistent with the design pressure for vessels and equipment to which it is attached.
3. P&ID REVIEW
At this point you can visualize and correct the existing P&IDs if they are not in as-built condition. As you redline the drawing, ask as many questions as possible such as:
a) What process liquid/gas will be going through the pipe?
b) Will the piping need to have new supports or can existing supports be utilized?
c) How many valves will need to be in the design?
d) What type of valves? Why?
4. PIPING SPECIFICATIONS
Piping Specifications are technical documents that provide the appropriate component selection and material grade of pipe, fittings and flanges. Piping Specs provide specific/additional requirements for the materials, components or services that are beyond the standard code requirements such as ASME B31.3. For Example, if you want A106 Gr B pipe with Maximum carbon of 0.23% against standard requirements of 0.3% Max, you must include this requirement in your purchase specification.
Normally, oil & gas facilities generate their own specification during FEED (Front End Engineering and Design) stage or sometimes use readily available client specifications from well-established companies such as Shell, Tesoro, Big West Oil and Chevron. They are also available from commercial entities such as Process Industry Practices (PIP.org).
5. DESIGN & LAYOUT
After proper planning, piping layout then becomes a matter of designing dimensioned routings from one point to another point with the branches, valves, piping specialties, and instrumentation required. The piping designer must be familiar with the proper installation of all types of valves. Valves should be installed with particular attention given to avoiding head and knee knockers, tripping hazards and how an operator would access the valve. The designer should also provide high-point vent and low-point drain connections for hydrostatic testing, for the evacuation of entrapped air, and line draining during maintenance shutdowns.
6. PIPE SUPPORTS
The five main functions of a pipe support are to anchor, guide, limit movement, absorb shock, and support any specified load.
New piping may require structural support, which means that piping should be located in close proximity to existing steel or concrete.
In a recent project, existing equipment had no support location within a 7’ radius. This was a challenge in itself because the connecting nozzle location for the new pipe was offset considerably from the nearest concrete column. With some unique designing the pipe had proper supports.
Always remember that piping designers route piping and components in a detail oriented fashion while keeping in mind potential unforeseen changes. The engineer is a resource during your design process and once approved everything should be fabricated and installed per the design you presented.