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Production of liners by making moldings with centrifugal casting

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On order to maximize the efficiency of drilling operations, and aware of the importance of implementing modern high-tech equipment, «Bursnab» Ltd. has developed a technology for production of bimetallic liners for drilling pumps by manufacturing moldings of centrifugal casting.

By the manufacture and testing of several prototypes and based on laboratory studies of the structure and composition of materials, the optimum composition of the steel outer and inner working layers of the liner was selected by our specialists, consisting of wear-resistant chromium-molybdenum cast iron, which has a several times smaller wear in abrasive environments than traditionally used steel have.

Fig. "The results of comparative tests of the durability of hardened CrMo cast iron and hardened high-carbon steel"

Laboratory tests revealed that the presence of an internal working layer, made of wear resistant cast iron, will reduce specification requirements of the steel used in terms of hardening and surface treatment. Working life of such a liner is up to 700-800 hours, depending on operating conditions.

After a series of industrial tests carried out on drilling platforms of «Gazprom» Ltd. and «Lukoil» Ltd. companies, we have registered specifications and certificate of conformity for these products and developed the industrial manufacture of centrifugally casted bimetallic liners for oil rig pumps.

We produce liners of the following types:

  • VB-590 - for UNB-600 and similar pumps;
  • VB-640 - for UNB-1180 and similar pumps;
  • VBT-400 - for NBT-475, NBT-600, NBT-600-II, UNBT-950 and similar pumps;
  • VBT-407 - for UNBT-950L, UNBT-950LI, UNBT-1180LI and similar pumps.

Look for details about oil rig pumps

Production of moldings by centrifugal casting includes following procedures:

1. Getting a bimetallic casting by sequential filling of the outer layer made of steel 25L and internal working layer of wear-resistant chromium-molybdenum cast iron. The existing installation of centrifugal casting and foundry tooling (molds) can now receive casting with inner diameter of 120-160mm. Thickness of the cast iron in the casting is 15-20mm.

2. Heat treatment (annealing) of the casting for the subsequent pre-machining. The hardness of the working layer after annealing is 35-40 HRC.
3. Pre-machining, including cutting of the original cast into shapes and processing of outer and inner diameters. Allowance for the final (finishing) treatment after peeling is 1,0-1,5 mm per side.
4. Hardening, providing reception hardness of the shell 53-60 HRC.
5. Final (finish) machining of casts.

The economic effect of bimetallic liners achieved by increasing of the turnaround time and thus, reducing maintenance cost. In 2009, using this technology we manufactured and supplied to the customers more than 2 thousand liners for the pumps of various revisions, more than a thousand pieces of which was bought by «Gazprom-drilling» for their own needs.

Apart of the bimetallic liners, range of the «Bursnab» products includes:

  • Oil rig pup rods;
  • Inlays for UNBT pumps;
  • Rod nuts.
At present, we develop the manufacture of cylinder liners to the oil rig pumps of foreign manufacturing.