In underground coal mining production, the hydraulic system is often regarded as the “power nerve” of mining machinery. However, frequent oil leaks in hydraulic systems have long plagued numerous coal mining enterprises—wasting hydraulic fluid, polluting the environment, severely impacting production efficiency, and even posing safety risks. So where does the root cause of these leaks lie? Extensive practice has proven that the key often lies in the hydraulic hoses—specifically, whether genuine MA-certified hoses are being used.
Underground coal mine working conditions are extremely harsh, posing multiple extreme challenges to hydraulic hoses. Large mining height hydraulic supports operate under extremely high working pressures with severe load fluctuations that generate intense pressure pulses. Falling rocks, collisions, and continuous friction are common occurrences. The presence of methane gas and coal dust underground requires all equipment components to possess flame-retardant and anti-static properties.
Under these demanding conditions, ordinary industrial hoses are far from meeting safety and performance requirements. If the hydraulic system is improperly configured, hydraulic components are of poor quality, the external environment is harsh, or operation and management are inadequate, the system is prone to fluid leakage, seal failure, and valve damage. Hose aging, substandard fitting processing quality, and seal wear are the three most common causes of leaks. Once a hose fails under high pressure, it can result in fluid injection, equipment loss of control, or even fire.
MA is China‘s Mining Product Safety Approval Mark (“Mei An” – Coal Safety), serving as a statutory market access certification for mining products sold in the Chinese market. According to the “Interim Measures for the Administration of Safety Signs for Coal Mine Products,” the mining product safety approval mark is the credential confirming that a mining product meets national and industry safety standards, permitting manufacturers to sell and users to use the product.
MA certification imposes extremely strict requirements on hydraulic hoses: products undergo end-to-end supervision from design and materials through production and testing to ensure compliance with China‘s mine safety regulations. Possession of the MA mark signifies that the product has passed rigorous review and testing by nationally authorized institutions.
Specifically, MA-certified hydraulic hoses are primarily tested against MT/T 98-2006 “Inspection Specification for Hoses and Hose Assemblies for Hydraulic Supports” and GB/T 3683-2011 standards. Product categories cover single-wire braid hydraulic hoses, double-wire braid hydraulic support hoses, triple-wire braid hydraulic support hoses, and four-wire spiral medium/high-pressure hydraulic support hoses. Different specifications correspond to different pressure ratings—for example, single-wire braid hoses handle 16-25MPa, double-wire braid hoses handle 12-45MPa, and four-wire spiral high-pressure hoses can reach 20-100MPa.
MA-certified hoses must meet critical performance indicators including flame resistance (self-extinguishing within 10 seconds after flame removal), anti-static properties (surface resistance ≤1×10⁹Ω), pressure resistance (no leakage at 1.5× working pressure for 5 minutes), and pulse durability (≥200,000 pressure cycles).
Many coal mining enterprises, in an effort to reduce costs, purchase “industrial-grade” hoses without MA certification as substitutes for mining hoses. These hoses fall far short of required performance standards in flame resistance, anti-static properties, pressure resistance, and wear resistance. In the high-pressure, high-impact, high-wear underground environment, the inner layer of non-MA hoses is easily eroded and abraded, leading to significant oil seepage. The outer layer lacks flame-retardant and anti-static formulations, potentially generating static sparks from friction and posing serious safety hazards.
More critically, non-MA hoses have poor pulse fatigue performance, aging and cracking rapidly under frequent pressure fluctuations, resulting in drastically shortened service life. This directly leads to frequent hydraulic system leaks, constant equipment downtime for repairs, and increased overall operating costs.
Check the Marking: Genuine MA-certified products bear the safety approval mark in a prominent position on the product body—the standard specification features a yellow background with a black border and “MA” characters raised 0.25mm. The safety approval number is printed below the pattern.
Verify the Certificate: Request the supplier to provide a valid Mining Product Safety Approval Certificate (MA Certificate) and verify it on the official website of the Mining Products Safety Approval and Certification Center.
Confirm the Standards: Check whether the hose complies with mining standards such as MT/T 98-2006 and GB/T 3683-2011.
Source from Authorized Channels: Only purchase from manufacturers or authorized distributors that hold valid MA certificates.
Frequent oil leaks in coal mine hydraulic systems are often not a matter of “can’t be fixed” but of “using the wrong hose.” Genuine MA-certified hoses strictly adhere to national mining safety standards from design and materials through production—they are the baseline for ensuring safe underground operations. Choosing MA-certified hoses means choosing safety, choosing efficiency, and choosing long-term, stable production operations.
