What are the requirements for stainless steel pipes in medical oxygen pipelines?

The requirements for stainless steel pipes in medical oxygen pipelines mainly involve multiple aspects such as material, specifications, performance, processing, and safety to ensure the safety, reliability, and cleanliness of oxygen delivery. The specific requirements are as follows:

1、 Material requirements

1. Stainless steel type

Prioritize the use of austenitic stainless steel (such as 304, 304L, 316, 316L) due to its excellent corrosion resistance, oxidation resistance, and non-magnetic properties, which can prevent rusting or metal particle detachment during oxygen transport.

The use of martensitic stainless steel (such as 410, 420) is prohibited due to its poor magnetic properties and corrosion resistance, which may pose safety hazards in high-pressure oxygen environments.

2. Chemical composition control

Carbon content (C): usually required to be ≤ 0.03% (such as 304L, 316L) to reduce the risk of intergranular corrosion.

Sulfur content (S) and phosphorus content (P) should be strictly limited (such as ≤ 0.03%) to avoid impurities affecting material strength and corrosion resistance.

2、 Specification and size requirements

1. Pipe diameter and wall thickness

The diameter of the pipe is determined based on the oxygen flow rate, pressure, and usage scenario (such as DN15-DN50 commonly used in hospital wards), and the wall thickness needs to meet the pressure bearing requirements and comply with GB/T 14976 "Stainless Steel Seamless Steel Tubes for Fluid Transport" or GB/T 12771 "Stainless Steel Welded Steel Tubes for Fluid Transport" standards.

High pressure oxygen pipelines (such as the main pipeline of the central oxygen supply system) need to use seamless steel pipes to ensure strength; Low pressure branch pipes can use welded steel pipes, but the welds must undergo non-destructive testing (such as radiographic and eddy current testing).

2. Surface roughness

The surface roughness (Ra) of the pipeline is ≤ 0.8 μ m, even ≤ 0.4 μ m, to reduce oxygen flow resistance and impurity adhesion, and avoid static electricity accumulation or spark generation.

3、 Performance requirements

1. Pressure resistance and strength

It is necessary to meet the design pressure requirements (such as the commonly used working pressure of medical oxygen of 0.2-0.6MPa), and pass the water pressure test (test pressure is 1.5 times the working pressure) and air pressure test to ensure no leakage.

The mechanical properties such as tensile strength and yield strength of the material must comply with relevant national standards.

2. Corrosion resistance

It is necessary to conduct intergranular corrosion tests (such as GB/T 4334) to ensure that corrosion does not occur in humid or oxidizing environments and to avoid rust contamination of oxygen.

4、 Processing and manufacturing requirements

1. Pipeline processing

Cutting: Mechanical cutting or plasma cutting is used, and burrs and oxide scales need to be removed after cutting to avoid residual debris.

Welding: Inert gas shielded welding (such as TIG welding) is used to ensure smooth and pore free welds. After welding, acid pickling and passivation treatment are required to enhance corrosion resistance.

Bend: Bend radius ≥ 3 times the pipe diameter to avoid scratching or deformation of the inner wall of the pipeline.

2. Cleaning and degreasing

Strict degreasing treatment (using solvents such as carbon tetrachloride and trichloroethylene) is required before pipeline installation to remove oil and grease, and prevent combustion or explosion caused by contact between grease and oxygen.

After cleaning, it should be sealed and stored to avoid secondary pollution. When installing, wear oil-free gloves for operation.

5、 Safety and installation requirements

1. Anti static and grounding

Stainless steel pipes need to be reliably grounded to avoid static electricity accumulation caused by oxygen flow, with a grounding resistance of ≤ 10 Ω.

The pipeline connection needs to be bridged with conductive strips to ensure static conductivity.

2. Identification and Protection

The outer surface of the pipeline should be painted with blue markings (medical oxygen standard color) and marked with warning words such as "oxygen" and "no oil".

When passing through walls or floors, protective sleeves should be added to avoid mechanical damage.

6、 Standards and Certification

It must comply with national standards (such as GB 50751 "Technical Specification for Medical Gas Engineering", GB 150 "Pressure Vessels") and industry standards (such as YY/T 0801 "Seamless Metal Pipelines for Medical Gas and Vacuum").

Some scenarios require third-party certification (such as ISO 13485 Medical Device Quality Management System Certification) to ensure that materials and processes meet medical requirements.

summarize

The stainless steel pipes used for medical oxygen pipelines need to be comprehensively controlled in terms of material, processing, performance, and safety protection. The core is to ensure the cleanliness and safety of oxygen delivery, and to avoid medical accidents caused by material defects or contamination. In practical applications, it is necessary to select suitable stainless steel pipes and strictly follow installation standards based on design specifications, usage scenarios, and regulatory requirements.

Tags: Material requirements, Specification and size requirements, Standards and Certification