Question: For the insulation padding of cold-temperature pipeline supports, red pine wood is not used – what material would be a better choice?

We use ordinary wooden pipe supports, which are soaked in asphalt.

This post was last edited by Albertlu on 2010-8-7 at 22:03. Bakelite can be used; it can be processed into various types of pipe supports, shims, and brackets. Bakelite is an artificial synthetic chemical substance, considered a type of plastic material, and can be used as material for light bulbs, switches, sockets, circuit boards, etc. Its characteristics include water resistance, electrical insulation, heat resistance, and high strength. Bakelite is made by mixing powdered phenolic resin with sawdust, asbestos, or clay, and then pressing the mixture into shape at high temperatures; phenolic resin was the world’s first artificially synthesized resin.

Pine wood soaked in asphalt is used as supports for low-temperature pipelines, as required by standards. If other materials are to be used instead, the issue of insulation must be taken into consideration; it’s sufficient if the insulation coefficient is equal to or greater than that of wooden supports. However, using pine wood supports doesn’t incur high costs and they are also easy to use – so why replace them? In practical applications, for pipelines carrying low-temperature media, if wooden supports aren’t used, you’ll find that from the supports all the way to the pipe rack and down to the ground, there’s ice and water, resulting in significant heat loss. The concept of energy conservation is very important; this shouldn’t be underestimated. Regarding what was mentioned on the third floor, you need to make it clear to the client that they are violating the design specifications. Once that’s made clear, it’s no longer your responsibility. If you’re not sure, does the client not have any process or equipment engineers? Don’t they understand this? I really don’t get it.

What are the standard specifications for red pine wood? Are there any requirements? The design office only specified 30 cubic meters, but no specific details were given – how should I proceed with the purchase?

High-density polyurethane HDPU or high-density polyisocyanurate can be used as a substitute for red pine. Currently, large design institutes in China use these materials for pipe supports and padding elements for insulation purposes. This is part of a solution I developed previously; you may consider it as a reference. Red pine insulation pads are used as supports for pipeline insulation, in accordance with the standards specified in HG.T21629-1999 \"Standard Drawings for Pipe Supports.\" However, this material tends to develop cracks and other defects when used in low-temperature environments. Our company recommends using the latest type of high-density polyurethane material as the insulation material. This material has stable properties, a uniform structure, and high load-bearing capacity; it also allows for easier and more secure bonding with the pipe insulation materials. ① Thermal conductivity: The thermal conductivity of HDPU is 0.05, while that of red pine is ≥0.15 (depending on the moisture content). In comparison, HDPU offers a better insulation effect. ② Water absorption rate: The water absorption rate of HDPU is ≤1.5%. Although red pine wood is treated with asphalt paint and waterproofing measures, over time these treatments lose their effectiveness, making the wood prone to absorbing water, deforming, and cracking. This leads to an increase in the thermal conductivity and higher heat loss. ③ Compressive strength: The compressive strength of HDPU is ≥6 Mpa, while that of Korean red pine is 1.9 Mpa. With prolonged use, the lower layers of Korean red pine blocks deform and shrink, creating gaps that allow cold air to pass through. ④ Flammability: The oxygen index of HDPU is >26, indicating flame retardancy, while red pine is self-igniting. ⑤ Acid and alkali resistance: HDPU can withstand strong acids and bases, while red pine is prone to decay in harsh environments. ⑥ Service life: HDPU can coexist with pipelines. ⑦ Linear expansion coefficient: The linear expansion coefficient of HDPU is closer to that of steel pipes compared to red pine. Moreover, under vibration, the HDPU becomes even more secure. ⑧ Construction: The HDPU bracket is easy to install; it can be placed directly on the saddle, serving both as a thermal insulation support and allowing for direct bonding and sealing with the external thermal insulation material of the pipeline. The red pine padding blocks need to be joined together in sets of 4 (or 8), and the gaps between them must be sealed with other materials; otherwise, if moisture gets in, the insulation effect will be poor.

Regarding the high-density polyurethane (DZHDPU) mentioned on the 7th floor, there is also another type of PE pipe support suitable for low-temperature pipes.