Just recently, I was talking with several customers who work with pipeline engineering. I see when selection the inner lining pipe they always be flustered on this question: Polyurethane Lined Pipe and Polypropylene Lined Pipe, which one is better? All the base materials is Spiral Seam Welded Pipe, but the inner lining materials are different, and the performance and price is so different.
Today, by taking the actual case of the Cangzhou Spiral Steel Pipe Factory as an example, I will clarify this matter thoroughly.
Let's start with the substrate. This is the base.
Regardless of whether the inner lining is made of PU or PP, the base material is always Spiral Seam Welded Pipe. There are many manufacturers in Cangzhou that produce this product, but only Cangzhou Spiral Steel Pipes Group Co., Ltd. can achieve a large scale. This company was established in 1993, covering an area of 350,000 square meters in Cangzhou, with a total asset of 680 million yuan and 680 employees. It can produce 400,000 tons of spiral steel pipes per year, with an output value of 1.8 billion yuan - this scale is significant in the domestic industry.
But what truly determines the lifespan of the pipeline is the three-layer coating system.
Many people only focus on the inner lining, but they overlook the three crucial steps: the primer, the adhesive, and the outer anti-corrosion layer. Let's go through them one by one.
Layer 1: Epoxy Resin Primer
This is sprayed in powder form and its thickness must not be less than 60 micrometers. Don't underestimate this thin layer. It is responsible for bonding with the steel pipe substrate. If the primer is not done properly, even if it is stuck very firmly on top, it won't be of any use.
Second layer: PE adhesive
This layer can be sprayed or extruded. The minimum thickness is 140 micrometers. There is a technical detail worth noting here: The peel strength requirements for powder spraying and extrusion processes are different. When purchasing, be sure to ask the supplier which process they use. Otherwise, if you pull it apart on site, it will peel off the skin, which would be a hassle.
Third layer: Polyethylene outer coating
This layer is the thickest and is constructed through sintering or by extruding through a tube or sheet. After coating, it must be cooled; otherwise, it will deform when squeezed during transportation. The total coating thickness varies depending on the pipe diameter. If the pipe is to be buried underground or subjected to significant mechanical loads, the minimum layer thickness should be increased by an additional 0.7 millimeters. The specific value is usually provided in a table by the manufacturer, and you can simply select according to it.
Back to the original question: PU lining or PP lining?
To put it simply, here is an experience-based advice: Polyurethane-lined pipes have better wear resistance and are suitable for transporting media containing solid particles, such as slurries and wastewater; Polypropylene lined pipes have stronger temperature resistance and chemical corrosion resistance, and are suitable for chemical media and high-temperature scenarios.
If the project budget permits, it is also possible to communicate with the manufacturer to develop a combined solution. However, the prerequisite is that the base material quality and the three-layer anti-corrosion coating of Spiral Seam Welded Pipe must be up to standard. The reason why the Cangzhou Spiral Steel Pipe Factory has been able to stand firm in this industry for so many years is, in essence, that it controls the entire process itself - rolling the base material, applying the coating, and assembling the inner lining - which is much more reliable than relying on suppliers who patch together their products.
There is no definite "right" answer when choosing a pipe, but there are correct approaches. I hope this article can help you avoid some unnecessary detours when choosing between PU and PP.
Post time: May-28-2026