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In the oil drilling industry, the mud pump serves as the core power equipment of the drilling system, and the mud pump liner in its fluid end directly withstands the continuous impact of high-pressure, highly abrasive drilling fluid. The mud pump bi-metal liner is a common type, and a detailed analysis of its materials, working conditions, and other aspects is provided below: Ⅰ. Material Classification of Mud Pump Bi-Metal Liners 1.Ordinary Ductile Cast Iron：Ductile iron (QT450-10, QT600-3) Core Properties: Tensile strength of 450-600MPa, elongation≥3%, good toughness, low cost, and easy bonding with the wear-resistant layer. Applicable Scenarios: Medium-low pressure working conditions (pump pressure ≤25MPa), such as conventional onshore oil drilling and construction sand-gravel transportation. 2.High-Strength Alloy Steel：42CrMo, 35CrMnSi, 20CrNiMo Core Properties: Tensile strength ≥900MPa, yield strength≥750MPa, resistance to high pressure, impact, and high temperature (≤300℃). Applicable Scenarios: High-pressure/extreme load working conditions (pump pressure 25-60MPa), such as deep/ultra-deep well drilling and high-pressure coal chemical slurry pumps. 3.Corrosion-Resistant Alloy Steel：316L, 2205 duplex steel, Hastelloy C-276 Core Properties: Contains elements such as Cr, Ni, and Mo, resistant to corrosive media like Cl⁻ and H⁺, and resistant to salt spray, strong acids, and alkalis. Applicable Scenarios: Combined corrosion-abrasion working conditions, such as offshore oil drilling, chemical acidic slurry transportation, and shale gas oil-based drilling fluid scenarios. Ⅱ. Application Scenarios of Mud Pump Bi-Metal Liners in Oil Drilling 1.Basic Application Scenario - Conventional Onshore Oil Drilling Conventional onshore drilling is the most widespread application scenario for bi-metal liners, mainly adapted to triplex single action mud pumps (F type drilling mud pumps) on onshore drilling platforms. They are used to transport water-based drilling fluids containing conventional cuttings (e.g., sandstone and mudstone particles). Working Condition Characteristics：The drilling fluid pressure is usually 15-30MPa, and the hardness of cutting particles is relatively low (typically HV500-800). However, the operation cycle is long (1-3 months per well), so the liner must continuously withstand "particle erosion wear and reciprocating friction" while balancing cost and service life. Value of Bi-Metal Liners The base material is ductile iron or low-alloy steel, ensuring the liner does not crack or deform under medium pressure and is compatible with the regular installation and disassembly requirements of onshore mud pumps. The working layer is made of Cr20-Cr26 high-chromium cast iron with a hardness of HRC55-62, whose wear resistance is 2-3 times that of traditional gray cast iron liners. This extends the liner replacement cycle from 15-20 days to 40-60 days, reducing the frequency of shutdown maintenance for onshore drilling and lowering labor and accessory costs. Typical Applications: Drilling operations in vertical and directional sections of onshore oilfield development wells and exploration wells. 2. High-Load Application Scenario - Deep/Ultra-Deep Well Drilling As oil and gas exploration advances to deep formations (well depth >4500m for deep wells, >6000m for ultra-deep wells), mud pumps must withstand higher pressure and stronger impact. mud pump Bi-metal liners have become essential components for such high-load working conditions, mainly adapted to high-pressure triple-cylinder or five-cylinder mud pumps. Working Condition Characteristics Extremely high pump pressure: To penetrate deep, hard rock formations, the drilling fluid pressure needs to be increased to 30-50MPa. The liner must withstand continuous high-pressure alternating stress and is prone to cracking due to insufficient strength. Intense friction and impact: The reciprocating speed of the piston in deep wells is faster (usually 1.2-1.5m/s), leading to significant frictional heat accumulation between the liner and the piston. Additionally, deep well cuttings (e.g., granite, quartzite) have higher hardness, sharply increasing the risk of erosion wear. High operation risk: The cost of deep well drilling is extremely high . Liner failure will cause long-term shutdowns and huge economic losses. Value of Bi-Metal Liners Adopts a high-strength alloy steel base material (e.g., 42CrMo) combined with a tungsten carbide-reinforced wear-resistant layer. The base material has a tensile strength ≥900MPa, enabling it to resist pressures above 50MPa without cracking. The wear-resistant layer undergoes centrifugal compounding and quenching, increasing its hardness to HRC62-65. Its impact wear resistance is 30% higher than that of conventional bi-metal liners, and the liner service life can be stably maintained at 35-50 days, meeting the "long-cycle, low-risk" operation requirements of deep wells. Typical Applications: Shale gas deep wells and deep oil-gas reservoir exploration wells. 3. Corrosion-Resistant Application Scenario - Offshore Oil Drilling In addition to high-pressure abrasion, the mud pump liners on offshore drilling platforms must resist the dual corrosion of the marine environment. Bi-metal liners are the core solution for such scenarios. Working Condition Characteristics Severe corrosive environment: The marine air contains high concentrations of salt (Cl⁻), and seawater easily mixes into the drilling fluid to form saltwater drilling fluid, causing electrochemical corrosion to the liner. Strict space constraints: The equipment installation space on offshore platforms is compact, so the liner must have high reliability and long service life to reduce the difficulty of offshore hoisting and replacement . Volatile working conditions: Offshore drilling is affected by wind and waves, leading to instantaneous fluctuations in mud pump pressure. The liner must have a certain degree of impact toughness. Value of Bi-Metal Liners The working layer is made of high-chromium cast iron with a nickel-based alloy coating. The nickel-based alloy coating forms a dense oxide film on the inner wall of the liner, blocking the corrosive penetration of high-concentration salt and improving salt spray corrosion resistance by more than 50% compared with ordinary high-chromium cast iron. The base material is corrosion-resistant low-alloy steel (e.g., 316L stainless steel composite base material), preventing the outer wall of the liner from rusting due to marine moisture corrosion. The overall service life is extended to 50-70 days, significantly reducing offshore maintenance costs. Typical Applications: Oil and gas drilling operations on shallow-water fixed platforms and deep-water semi-submersible platforms . 4. Chemical Corrosion-Resistant Scenario - Drilling with Special Drilling Fluids When oil drilling uses oil-based drilling fluids, synthetic-based drilling fluids, or acidic drilling fluids, ordinary liners are prone to failure due to chemical corrosion. Bi-metal liners require targeted material formula optimization to adapt to such scenarios. Working Condition Characteristics Strong chemical corrosion: Oil-based drilling fluids contain mineral oil and emulsifiers, which easily decompose to produce acidic substances under long-term high temperatures (drilling fluid temperature up to 80-120℃), corroding the inner wall of the liner. Organic solvents in synthetic-based drilling fluids can soften the surface layer of ordinary metals. Synergistic abrasion-corrosion effect: Special drilling fluids are usually combined with high-specific-gravity weighting agents (e.g., barite powder, hardness HV800-1000). The liner must resist the combined damage of "chemical corrosion + particle abrasion," and its failure rate is 2-3 times faster than that under conventional working conditions. Value of Bi-Metal Liners The working layer adopts a "Hastelloy+wear-resistant ceramic particle composite layer." Hastelloy (e.g., Hastelloy C-276) has excellent resistance to oil, organic solvents, and acids, while ceramic particles (e.g., Al₂O₃) enhance wear resistance with a hardness of HRC65-70, capable of withstanding the erosion of weighting agents. The vacuum composite casting process ensures tight bonding between the working layer and the base material, avoiding interlayer peeling caused by chemical corrosion. The service life can be extended to 45-60 days, meeting the long-term operation requirements of special drilling fluids. Typical Applications: Shale gas horizontal wells (oil-based drilling fluids) and acidic oil-gas reservoir drilling (e.g., oil-gas wells containing H₂S and CO₂, requiring acid-resistant drilling fluids). Ⅲ. Advantages of Bi-Metal Liners Shortcomings of Single-Metal Liners:Ordinary cast iron liners have poor toughness and insufficient wear resistance; pure high-chromium cast iron liners, though wear-resistant (HRC55-62), have extremely high brittleness (impact strength <15MPa) and are prone to cracking under high pressure; ordinary steel liners have sufficient strength but their surfaces are easily grooved by particle erosion, resulting in short wear life. Advantages of Mud Pump Bi-Metal Liners:Base materials such as ductile iron and 42CrMo alloy steel provide sufficient tensile strength and toughness (elongation≥3%), ensuring the liner does not crack or deform under high-pressure (30-50MPa) and impact working conditions. Under conventional oil drilling conditions, the service life of bi-metal liners can reach 40-60 days, which is 2-3 times that of ordinary cast iron liners. Corrosion Shortcomings of Single-Metal Liners:Ordinary high-chromium cast iron liners rust within one month in the marine salt spray environment; pure stainless steel liners, though corrosion-resistant, have poor wear resistance and are prone to wear failure within 10 days in sand-containing mud. Advantages of Bi-Metal Liners:Corrosion-resistant alloy steels (e.g., 316L, 2205 duplex steel, Hastelloy) are used to form a dense oxide film on the surface, blocking the penetration of corrosive media such as Cl⁻ and H⁺. The working layer is combined with a ceramic coating (Al₂O₃) to further enhance surface corrosion resistance while maintaining high hardness to resist particle abrasion. In offshore oil drilling scenarios, the service life of bi-metal liners can reach 50-70 days, which is 2.5-3.5 times that of ordinary high-chromium cast iron liners, and liner leakage failures caused by corrosion are avoided. Ⅳ. Selection Guide Step 1: Clarify Your Own Working Conditions First, sort out the core working condition information, then select parameters accordingly to avoid blindly choosing high-priced products or low-priced but non-durable products: 1. Equipment Parameters: Pump model (e.g., F-1600 mud pump), working pressure (MPa), piston diameter (must match the liner inner diameter). 2. Medium Characteristics: Slurry type (e.g., drilling fluid, slag slurry), particle size (mm), corrosion (whether it contains acid/salt/organic solvents). 3. Operation Requirements: Expected liner service life, equipment shutdown cost. Step 2: Screen According to Working Conditions and Parameters Select key parameters based on the working conditions identified in Step 1: Onshore Oil Drilling: Inner diameter 150mm + high-chromium cast iron working layer (HRC58) + ductile iron base material. Offshore Oil Drilling: Inner diameter 180mm + nickel-based alloy working layer (HRC60) + 2205 duplex steel base material. Mining Slurry Pumps: Inner diameter 200mm + tungsten carbide working layer (HRC68) + 42CrMo base material. Chemical Acidic Slurry: Inner diameter 120mm + nickel-based alloy working layer (HRC58) + 316L base material. Step 3: Request 3 Types of Certification Documents Request written documents from suppliers to verify the authenticity of parameters: Material Certificate (MTC): Confirm the actual materials of the working layer and base material. Performance Test Report: Include test data on hardness (HRC), bonding strength, roughness, and roundness. Working Condition Cases: Request application cases from the same industry to confirm whether the service life meets requirements. Step 4: Balance Unit Price and Total Cost, Not Just Focus on Low Prices Example: The unit price of an ordinary high-chromium cast iron liner is approximately 280 US dollars, with a service life of 45 days, resulting in a unit time cost of roughly 6.22 US dollars/day. The unit price of a low-quality liner is around 210 US dollars, with a service life of 20 days, resulting in a unit time cost of 10.5 US dollars/day, which is actually more expensive. If the equipment shutdown cost is high, prioritize mid-to-high-end products with "low unit time cost" rather than simply pursuing low prices.