General application pipes: a guide on electric-welded pipes for PUF
To apply the PUF insulation, we use two types of steel pipes, electric-welded and seamless. These pipes are further divided into a number of subcategories. In this article we focus on general application electric-welded pipes.
Types of electric-welded pipes
Welded pipes are manufactured using a longitudinal or spiral weld.
Spiral welded pipes have multiple application restrictions, and are used very rarely. Most often, longitudinal welded pipes are used for insulation – general application, water and gas and trunk line pipes.
Electric-welded general application pipes
General application pipes are the most common type of pipes. Their manufacture is regulated by GOST 10704-91, 10705-80 and 10706-76.
They are divided into groups:
- А — with rated mechanical properties.
- Б — with rated chemical composition.
- В — with rated mechanical properties and chemical composition.
- Д — with rated hydraulic test pressure.
We purchase and insulate group B pipes. They are the most expensive because of their superior quality confirmed by the corresponding tests.
Diameters
The schedule of electric-welded general application pipes offers 77 outside diameters between 10 and 1420 mm, but typically we deal with 13 sizes that are widespread in our industry.
Below are the main diameters and wall thicknesses (units of measurement are millimeters; the most common sizes are in bold):
- 57 – 3,0; 3,5; 4,0;
- 76 – 3,0; 3,5; 4,0;
- 89 – 3,0; 3,5; 4,0;
- 108 – 3,0; 3,5; 4,0; 4,5; 5,0;
- 133 – 3,5; 4,0; 4,5; 5,0; 6,0;
- 159 – 4,0; 4,5; 5,0; 6,0;
- 219 – 5,0; 6,0; 7,0; 8,0;
- 273 – 6,0; 7,0; 8,0;
- 325 – 6,0; 7,0; 8,0; 9,0; 10,0;
- 377 – 6,0; 7,0; 8,0; 9,0; 10,0;
- 426 – 6,0; 7,0; 8,0; 9,0; 10,0;
- 530 – 6,0; 7,0; 8,0; 9,0; 10,0;
- 630 – 6,0; 7,0; 8,0; 9,0; 10,0.
It does not mean that we never use other standard sizes of pipes, simply that these pipes are most common and are frequently in stock,and are rolled more often than others. For example, steelworkers run batches of pipe 377 with a 9.0 wall only once in a quarter if sufficient quantities have been ordered, hence these pipes are rarely available from the suppliers in stock.
Lengths
Length is another important parameter. It is different for each diameter and for each individual pipe.
To calculate the pipe quantity, which we need to determine the loading of trucks, we use average values as a guide:
- 57 – 9,4 m;
- 76, 89, 108, 133, 159 – 116 m;
- 219, 273, 325, 377, 426, 530, 630 – between +/- 11,6 до +/- 12 m.
Requirements
The main requirements to materials, characteristics, tolerances, acceptance and storage, as well as to allowable defects and variations, are listed in GOST 10705-80.
- Carbon grade pipes must undergo heat treatment or hot reduction. However, there are exceptions, such as Ст1 grade pipes are not heat treated. Pipes made of low-alloy steel may be treated or untreated at the manufacturer’s discretion.
- Pipe surface must be free of cracks, slivers, laps, scabs and guide marks.
- Solidified metal beads (flash) must be removed.
- For pipes of diameter 159 and higher a welding bevel is mandatory if the wall thickness is 6.0 or over. Pipes of small diameter and thickness have no bevel, they are simply cut at a square angle.
SAVERHOT is an official dealer of major Russian steel plants, so we always keep between 2,500 and 4,000 tons of pipes in stock at our warehouse. We continuously replenish our stock with commonly used items. The data on availability are always relevant as they are updated from the ERP system in real time.
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