In the field of oil drilling, large-diameter hoses are the core components that connect drilling rigs, mud pumps, and wellheads, and their performance directly affects drilling efficiency and operational safety. With the increasing demand for deep, ultra deep, and offshore drilling, large-diameter hoses certified by the American Petroleum Institute (API) have become a popular choice in the industry due to their anti-static, explosion-proof, and high voltage resistance properties. This article analyzes the innovative breakthroughs and industry value of such hoses from three dimensions: technical standards, safety design, and application scenarios.

 
1、 API Certification: Quality Baseline for Oil Drilling Equipment
1.1 Strictness of API Standards
API certification is an authoritative technical specification in the global petroleum equipment field, covering the entire chain of materials, structures, performance, and more. Taking API 7K "Drilling Equipment Specification" as an example, the core requirements for large-diameter hoses include:
 
Pressure bearing capacity: The rated working pressure should cover the range of 35MPa to 105MPa, and the burst pressure should reach more than 4 times the rated value. For example, a 12 inch hose successfully withstood an instantaneous pressure of 420MPa in laboratory testing, far exceeding conventional requirements.
Pulse life: It is required to complete 2 million pulse cycles under rated pressure without leakage or structural damage. A domestically produced hose has increased its pulse life to 3 million times by optimizing the wire winding angle, reaching an international leading level.
Environmental adaptability: It needs to maintain flexibility at low temperatures of -40 ℃, without thermal decomposition at high temperatures of 120 ℃, and withstand corrosive gases such as H ₂ S and CO ₂. For example, the rubber layer inside the hose of Litong Hydraulic is made of hydrogenated nitrile rubber (HNBR), and the swelling rate is controlled within 3% in a medium containing 15% H ₂ S.
1.2 Technical barriers to certification process
Obtaining API certification requires passing three layers of review:
 
Material testing: The inner adhesive layer must pass ASTM D471 standard, and after soaking in IRM903 oil for 70 hours, the volume change rate should be ≤ 10%; The reinforcing layer steel wire must meet the ISO 18752 standard, with a tensile strength of ≥ 2100MPa and an elongation rate of ≤ 8%; The outer adhesive layer must pass the UL94 V-0 flame retardant test to ensure self extinguishing within 30 seconds.
Structural verification: Taking a four layer steel wire wrapped hose as an example, each layer of steel wire needs to be cross woven at a 54.7 ° golden angle to form a three-dimensional pressure bearing network. Experimental data from Tianjin Dingbao Petroleum Machinery shows that this structure can reduce the bending radius of the hose to 6 times the diameter of the pipe, while withstanding a pressure of 80MPa without deformation.
Life assessment: 500 hours of continuous pressure testing and 100000 dynamic bending tests need to be completed under simulated operating conditions. For example, a certain type of hose has a wear rate of less than 0.08mm/100h in a medium containing 20% quartz sand, and its service life is 1.5 times the industry average.
2、 Anti static and Explosion proof: Dual Protection from Materials to Structures
2.1 Inner adhesive layer: the "layer barrier" of conductive network
Static electricity is prone to accumulate in petroleum media, and if the voltage exceeds 300V, it may cause an explosion. Large caliber hoses achieve anti-static properties through the following technologies:
 
Doping of conductive materials: Add conductive carbon black or nano copper powder to the inner adhesive layer to control the surface resistance below 10 ΩΩ. For example, the measured resistance of the rubber layer inside the hose of Hebei Chaoran manufacturer is 8.5 × 10 ⁵ Ω, which is far lower than the upper limit of 1 × 10