July 24, 2026
Natural Gas vs. Oil and Refined Products Pipelines
Natural gas, oil, and refined products pipelines share the same build sequence but differ in testing, coating, and product handling. Here is what changes.
Key takeaways
- Natural gas, crude oil, and refined products pipelines follow the same basic construction sequence, but the product decides what changes along the way.
- Hydrostatic testing parameters and schedules are not identical across a gas line and a liquid line.
- Coating and corrosion control needs shift depending on what the pipe will carry and the ground it runs through.
- A contractor experienced across all three product types has fewer blind spots than one that has only ever built gas lines.
- Ask a contractor directly about their history with your specific product, not just pipelines as a general category.
A gas utility and a midstream operator were reviewing bids for two separate projects last year, a distribution line for one and a short liquids line for the other, and both companies assumed they were shopping for the same kind of contractor. On paper, the two projects looked alike: pipe, a right-of-way, a route from one point to another. It was not until the bids came back with different testing timelines and different coating specs that anyone stopped to ask why.
The answer is simple once someone explains it, but almost nobody does. Pipeline construction follows the same basic sequence no matter what the line will carry. Clear and grade the right-of-way, string and weld the pipe, coat and inspect the welds, lower it in, backfill, test it, and restore the land. That part does not change. What changes is tied to the product itself, and if you are comparing contractors or bids, it helps to know where those differences actually show up.
We build for natural gas, crude oil, and refined products, on both transmission and distribution scopes, so this is a question we field often from operators, developers, and anyone hiring a pipeline contractor for the first time. Here is what is actually different, and what is not.
The construction sequence does not change
Start with what stays the same, because it is most of the job. Whatever the pipe will carry, the stages of building a line run in the same order. The right-of-way gets cleared and graded. Pipe is strung out along the ditch and bent to the terrain. Welders join it into a continuous line, and every weld gets inspected before the joint is coated. The line gets lowered into the trench and backfilled, then tested, then the ground gets restored.
A crew running a spread for a gas line and a crew running a spread for a crude oil line are doing recognizably the same work in the same order. The skills that matter, reading the ground, keeping the welds tight, keeping the spread balanced so no one crew gets ahead of another, apply regardless of what eventually flows through the pipe. That is why a contractor with deep experience in one product is not starting from zero on another. The fundamentals carry over.
Where the differences actually start
The differences show up in the details layered on top of that sequence, not in the sequence itself. Two things drive most of them: how the product behaves under pressure, and what happens if something goes wrong.
Natural gas is a compressible gas. If a gas line fails, the gas expands and disperses. Crude oil and refined products are liquids, and if a liquid line fails, the product does not disperse the same way, it pools, it can travel with water or terrain, and cleanup looks completely different. That single difference in behavior is the root of most of the construction and design decisions that follow, from how the system is designed to fail safe to how monitoring and leak detection get built into the project.
None of this changes how the trench gets dug. It changes what the engineering calls for and what the testing and inspection plan has to prove before the line goes into service.
That difference in behavior also shapes decisions made before construction even starts. Depth of cover, setback distances from occupied structures, and how close a line can run to a water source or a populated area are all influenced by whether the product is a gas or a liquid. None of that shows up in the trench itself, but it shows up in the route that gets approved and the permits that get pulled before a single foot of pipe goes in the ground.
Testing looks different depending on the product
Every new pipeline gets hydrostatically tested before it goes into service. The line is filled with water, pressured up above its operating pressure, and held to prove there are no leaks or weak spots in the pipe or the welds. That part of the process is common across gas and liquid lines.
What is not identical is the specifics: the pressure the line is tested to, how long it holds, and how the results get documented and verified all trace back to the design basis for that particular product and that particular system. A liquids operator and a gas utility are not working from the same numbers, even though the equipment on site and the general method look similar. A contractor that has actually run testing programs for both knows where those numbers diverge and does not have to relearn it mid-project.
Coating, corrosion, and ground conditions
Coating protects the pipe from corrosion, and corrosion control gets specified differently depending on the product, the operating pressure, and the ground the line runs through. A crude oil or refined products line often carries additional corrosion monitoring built into the design, because the consequences of an undetected corrosion problem on a liquid line are treated more seriously in the engineering.
Ground conditions add another layer on top of the product itself. A line running through wet or unstable soil needs buoyancy control regardless of what it carries, but the coating and weighting specs still trace back to the product-specific design. This is one more reason coating and weight installation tends to be planned in from the start rather than added later. Getting it wrong is expensive to fix once the pipe is in the ground.
Cathodic protection, the electrical system that keeps buried steel from corroding over time, gets applied to both gas and liquid lines, but the monitoring intervals and the acceptance criteria are not automatically interchangeable between the two. A contractor building a corrosion control system for a crude oil line without adjusting for that difference is building the wrong system, even when the equipment on site looks identical to what goes on a gas line.
The regulatory picture is not one-size-fits-all
Gas pipelines and liquid pipelines answer to different regulatory frameworks, and that shapes decisions all the way down to how the project gets documented and inspected. A contractor that has only worked in one of those worlds can find the paperwork and inspection expectations of the other genuinely unfamiliar, even though the physical construction work looks similar on the surface.
This is not a reason to avoid a contractor that specializes in one product. It is a reason to ask directly. If your project is a liquids line and the contractor you are talking to has built almost entirely gas pipelines, that is worth a direct conversation about their specific experience before you sign anything.
Why building across all three is worth asking about
There is a practical advantage to working with a contractor that self-performs across gas, crude oil, and refined products instead of specializing narrowly in one. The crews and superintendents who have run testing programs, coating specs, and inspection requirements across different products carry that judgment onto the next job, even when the next job is a different product than the last one. Fewer blind spots means fewer surprises once the engineering meets the ground.
It also means one point of contact if your organization handles more than one product type, which is common for midstream operators and gas and energy operators running mixed systems. You are not stuck explaining your project from scratch to a contractor who has never built for that product before.
That experience also shows up in smaller, practical ways. Ordering the right coating material the first time. Scheduling a testing window that matches what the product actually requires instead of a generic timeline. Knowing which inspection items an operator’s engineering team is going to ask about before they ask. None of it is dramatic, but all of it adds up to fewer change orders and fewer surprises once the project is underway.
What to ask before you compare bids
If you are comparing pipeline contractors and your project is not a straightforward gas distribution line, ask two things directly. First, ask what products they have actually built for, by name, not just how many miles of pipeline they have in the ground. Second, ask them to walk through how testing and coating requirements would differ for your specific project compared to a job they have done for a different product. A contractor who answers in specifics has done the work. One who answers only in general pipeline terms has not necessarily built what you are building.
Natural gas, oil, and refined products pipelines are more alike than different in how they get built, but the differences that do exist are not cosmetic. They show up in testing, coating, and the regulatory expectations layered over the construction. Knowing where to ask the question is most of the battle.
If you have a natural gas, crude oil, or refined products project on the table and want a straight read on what it will take, request a bid or just tell us about the job. Even a route on a map and a product type is enough to start the conversation.
Frequently asked questions
What is the real difference between a natural gas pipeline and an oil pipeline?
The construction sequence, clearing, stringing, welding, coating, lowering in, testing, and restoring, is the same for both. What changes is how the line is tested, how it is coated and protected, and some of the safety and operating considerations tied to what is actually moving through the pipe.
Do refined products pipelines get built differently than crude oil lines?
The core construction steps are similar for crude oil and refined products, since both are liquid pipelines. The differences tend to show up in testing details and in how the operator specs corrosion protection and monitoring, not in the fundamental way the pipe goes into the ground.
Can the same contractor build both gas and liquid pipelines?
Yes, and it is worth asking whether a contractor actually has. A contractor that has only ever built gas lines may not have the same depth of experience with the testing and coating requirements that come with a liquid line, and the reverse is also true.
Why does the product matter if the pipe is just going in a ditch either way?
Because what happens before and after the pipe is in the ditch is not identical. Testing pressures and hold times, coating specifications, and how the system is designed to fail safe all depend on whether the line is carrying gas, crude, or a refined product.
What should I ask a contractor about experience with my specific product?
Ask them to walk through projects they have built for that exact product, not pipelines in general. A contractor who can speak specifically to gas, crude, or refined products work has actually done it. One who answers only in general pipeline terms may not have.