So when we say thermal expansion pipe usually it is referred to the pipe made in seamless. Since it is preferred to use seamless pipe than welded pipe in some pipelines or modern constructions, thermal expansion pipe is a divine option to the people who regularly need a good quality steel pipe.

thermal expansion manufacturing processes

The production process of the thermally expanded steel pipes is consisting of few steps.

Original seamless manufacturing part

1.The main raw material in case of producing the seamless thermal expansion pipes is steel. Steel is obtained from iron. There may be other materials that can exist along with the steel. For example, manganese, aluminium, zirconium etc.

2.The next step after the raw steel is to turn them usable steel. Well, whether it is the production process of welded or seamless pipes, the starting occurs at the casting of the raw steel into a more workable form. The molten steel is obtained by the melting of the iron ore along with coke in a furnace. Then the carbon is removed by the help of blasting oxygen in liquid. The molten steel is then poured into iron moulds to get ingots.

3.Next, the ingots are putted in a machine where it is pressed and turned into thinner and longer pieces of steel. The thinning and elongation process continues till the desired size of the steel is obtained. The steel is flipped so the steel is even on both sides.

4.The later process is the cutting of the uneven ends. Here, both the uneven ends are cut off and the blooms are cut off into shorter pieces. These blooms are then processed further to make the thermal expansion pipe.

Hot rolled part

5.It is then turned into a pipe by the stretching of the steel out. In case of the seamless pipes, the primary concern is to, stretch the steel and form it into a pipe. The round billets are heated to around 1204 degree Celsius. The steel reach to such state where it is easy to stretch. The stretching is done with the help of a special type of roller.

6.Then next is spraying water on the hot pipes. For taking them back to the normal stage, cold water is sprayed evenly on the pipes. The pipes are then painted or given finishing for a good outer look.

Thermal Heated Part (Hot expanding processes)

Because of the limits from seamless steel pipe manufacturers, the largest hot rolled seamless pipe normally below 457 mm, or 508 mm. So if you are seeking for the seamless pipe larger than this dimensions, we have to do hot expansion to the original (mother) seamless pipe. So another of thermal expansion pipe is coming into market.

It is to use the heat generated from mid-frequency heating machine, expanded by a expansion equipment, expanding pipe to a certain diameter that we required.

With the advantages of high efficiency, lower cost and seamless quality, this type of thermal expansion seamless pipe has been quickly accepted by the customers worldwide.

Requirements for thermal expansion pipe is increasing

The uses of thermal expansion pipe are increasing day by day. Though the price is a bit higher than the welded ones but it is more beneficial to use them because they are not just safe and reliable but will also go a long way.

In most cases large diameter steel pipe is made in welded like LSAW pipe or SSAW pipe; More over, it also could be made in seamless by using hot expanding processes.

It shall be noted that for a high pressure pipeline large diameter seamless pipe is preferred. Since in welded type it is not expected as seamless types to bear the big pressure (the weakest point of the welded pipe is the welded seam on it). The welded seam can break or crack at anytime hence, people are looking for seamless large pipes for various things.

Material Standard

Almost all the steel material could used for making large diameter pipe, listed as blow for Carbon Steel, Chrome Moly Alloy pipes:

API 5L B, X42, X46, X52 to X80.
ASTM A53B
ASTM A252 Grade 2, 3
ASTM A671
ASTM A672
ASTM A691
ASTM A106B

Large Diameter Stainless Steel Pipe

Large diameter stainless steel pipe also required for a lot of industries, for liquid transmission, machine parts make. Mostly made in tig weld, material standard ASTM A312 or EN 10088-3. Grades in:

TP304/L/H, S30400, S30403, S31409
TP316/L/H, S31600, S31603, S31609
TP310S/H, S31008, S31009
TP321/H, S32100, S32109
TP347/H, S34700, S34709
904/L

Large diameters refer to pipe above 457 mm (16 inch) and 508 mm (20 inch)

As we know maximum diameters for ERW pipe usually is 457 mm 16 inch, so we can say the pipe diameters is larger than this OD are known to be large diameters pipes.

For LSAW and SSAW large steel pipe: From 508 mm 20 inch to 2540 mm 100 inch.

For large diameter seamless pipe also refer to the pipe that more than 16 inch or 20 inch. Since the pipe larger than these sizes, will not be manufactured only by hot rolling, an additional process hot expanding will be applied. This way could enlarge the pipe diameters in a short time, with low cost and high efficiency, therefor it has became a modern way of manufacturing large seamless pipes.

Hot expanding

Hot expanding process also known by thermal expansion process. It is to heat the pipe into a near transformation temperature, use corner skew rolling method or hot drawing method to expand seamless pipe diameters.

Notes before purchase large diameter seamless pipe

If you do not have ideas about the large diameter seamless pipe then it is very hard to buy one with good quality. Therefore, it is very important to know about it before purchasing.

1. Must not have seam on pipe body.

The seamless pipe must not have weld seam (some people remove the seam in an undetectable way and be careful of this). Large diameter seamless pipe shall be constructed in a specific process. Raw material should be a solid and round billet. Then, the billet is heated at a very high temperature but one should be careful while doing so because if the temperature rises to melting point then billet may melt. The billet after heating is stretched and pulled over until it takes the shape of a hollow tube. As the welded pipes are conventional, your contractor may suggest you to buy the welded ones but you have to be very careful and choose the seamless large pipe.

2. Roundness shall be noted

The next thing is the uniformity of shape of the seamless pipe. As the welded seam pipes are wrapped around another form before welding and as welding needs stress, heat and other external variables for the whole process of forming, it is very tough to get a welded pipe that is exactly round in shape. The seamless steel pipe is the continuous extrusion of alloy which signifies that you will just a get a round cross section that is necessary when you are using them for any construction process or installing pipes.

3. Large Seamless pipe bear big pressure than large welded pipe

The strength of the seamless pipe is more than the welded pipes. Well, you might find it quite expensive but, trust our examination; this is more reliable even under pressure. The welded pipes have the chance to break when in pressure but you can trust the large diameter seamless pipe without any doubt. The empty pipes always support of its own weight but when the pipe is filled with material or under load, it also supports the weight as well. Mostly leaks and pipe failures occur in case of the welded pipes. The seamless pipes does not have the seam hence, there is no chance of pipe failure.

4. Big diameter seamless pipe can working in harsh conditions

One of the best attributes of the seamless large pipes is that, it has the capability to work under extremely cold or extremely hot environment whereas, it is quite impossible for the welded pipes to work in extremely harsh condition.

Cost differences for large diameter pipes in different types

Large seamless pipes after hot expanding, the price is lower than normal hot rolled seamless pipe, (steel density reduced). But is higher than large welded pipes like SSAW and LSAW pipe.

Though the price of the large diameter seamless pipe is bit higher than the welded ones but the increasing ability and benefits are making it appropriate for any usage. In the array of commercial application of pipes, the importance of the seamless large pipes are increasing including pipelines oil rigs, building of ships, offshore rigs, machinery parts, pressure vessels, parts of machineries, equipment of oil field etc.