Steel Pipe Materials

For sour service, National Association of Corrosion Engineers (NACE) MR-01-75 requires that steel material have a Rockwell C hardness of less than 22 and contain less than 1% nickel to prevent sulfide stress cracking. 

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Fig. 4-2(1) Example of a tensile stress-strain curve for mild steel pipe material.

Table IX-5B Carbon Steel Piping Materials Performance Factor, Mf...

Fig. 3. The oriented microstructure of the duplex strainless steel pipe material.

Stress-strain (S-S) analysis of the materials provides important information. The tensile S-S curve (Figure 8.10) for steel-pipe material... 

Stress-strain (S-S) analysis of the materials provides important information. The tensile S-S curve for steel-pipe material identifies its yield point that is used as the basis in their design. Beyond this static loaded yield point (Chapter 2) the steel will enter into the range of plastic deformation that would lead to a total collapse of the pipe. The allowable design strain used is about two thirds of the yield point. 

The presence of these acids in crude oils and petroleum cuts causes problems for the refiner because they form stable emulsions with caustic solutions during desalting or in lubricating oil production very corrosive at high temperatures (350-400°C), they attack ordinary carbon steel, which necessitates the use of alloy piping materials. 

For pipelines in service in chemical plants, it is not usually convenient to place a radiation source inside the pipe and position it to irradiate each welded joint. The radioisotope source container maybe placed on the outer surface of the pipe. The radiation beams then pass through two pipe wall thicknesses to expose films placed diametrically opposite the radiation source, also on the outside of the pipe wall. Other methods, such as magnetic particle inspection of welds in steel pipe, or ultrasonic inspection of welds in pipes of all materials, supplement x-rays in many critical appHcations. The ultrasonic tests can often detect the thin, laminar discontinuities parallel to the pipe surface or the incomplete fusion discontinuities along the weld... 

Shipment, Stora.ge, ndPrice. l-Methyl-2-pyrrohdinone is available in tank cars or tank trailers as well as in dmms. Shipping containers are normally of unlined steel. Rubber hose is unsuitable for handling standard steel pipe or braided steel hose is acceptable. Ordinarily 1020 carbon steel (0550) is satisfactory as a storage material. Stainless-steel 304 and 316, nickel, and aluminum are also suitable. MethylpyrroHdinone is hygroscopic and must be protected from atmospheric moisture. In September 1994, NMP was Hsted at 3.89/kg. 

Oleum Equipment ndPiping. The traditional material of constmction for oleum is carbon steel. Relatively low oleum velocities must be used in steel piping to prevent excessive corrosion. The corrosiveness of oleum decreases with increasing SO concentration. Eor oleum concentrations <5% SO, carbon steel is not recommended because of excessive corrosion. Steel is borderline from 5% to about 15% SO, depending on temperature. 

Carbon steel is not normally a suitable piping material for concentrated sulfuric acid because of high corrosion rates in flowing acid. However, where temperatures and flow rates are low, heavy waU steel pipe is sometimes used for transferring product acid. 

Lead and Lead-Lined Steel Pipe Lead and lead-hned steel lipe have been essentially eliminated as piping materials owing to lealth hazards in fabrication and installation and to environmental objections. Lead has been replaced by suitable plastic, reinforced plastic, plastic-lined steel, or high-alloy materials. 

Cost rules out almost all alternative materials for long-distance pipe lines it is much cheaper to build and protect a mild steel pipe than to use stainless steel instead - even though no protection is then needed. The only competing material is a polymer, which is completely immune to wet corrosion of this kind. City gas mains are now being replaced by polymeric ones but for large diameter transmission lines, the mechanical strength of steel makes it the preferred choice. 

The electrolysis protection process using impressed current aluminum anodes allows uncoated and hot-dipped galvanized ferrous materials in domestic installations to be protected from corrosion. If impressed current aluminum anodes are installed in water tanks, the pipework is protected by the formation of a film without affecting the potability of the water. With domestic galvanized steel pipes, a marked retardation of the cathodic partial reaction occurs [15]. Electrolytic treatment alters the electrolytic characteristics of the water, as well as internal cathodic protection of the tank and its inserts (e.g., heating elements). The pipe protection relies on colloidal chemical processes and is applied only to new installations and not to old ones already attacked by corrosion. 

All subsequent green coke operations were made in a second coker, which was fashioned from steel pipe approximately 18 cm in diameter and 25 cm in length. A metal plate was welded to one end and a metal collar was welded to the other end such that a steel lid could be bolted to the system. Typically, about 250 to 500 g of pitch were sealed imder nitrogen in the coker reactor and the system placed in a large temperature-programmable furnace. The heat treatment process was as follows. The temperature was raised 5°C/min to 350 °C and then l°C/min to 425°C and the temperature held at 425°C for 90 minutes. Finally the temperature was raised further at 3°C/min to between 500 and 600°C, and held there for 3 hours. The coker was cooled to room temperature and the material recovered to determine green coke yield. 

Friction factor in long steel pipes handling wet (saturated with w ater vapor) gases such as hydrogen, carbon monoxide, carbon dioxide, nitrogen, oxygen and similar materials should be considered carefully, and often increased by a factor of 1.2 to 2.0 to account for corrosion. 

Plates, Shapes, and Bar Stock. Structural material used in the manufacture of main load carrying components of the equipment shall conform to applicable ASTM or API specifications covering steel shapes, plates, bars, or pipe, or a proprietary specification conforming to the minimum requirements of applicable ASTM or appropriate standard. Structural steel shapes having a specified minimum yield strength less than 33,000 psi, or steel pipe having a specified minimum yield strength less than 35,000 psi shall not be used. 

Pipe material (if this is not known, an assumption that it is steel will normally be sufficiently accurate). 

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