What requirements do the new energy business models have for stainless steel pipes

In the new energy business sectors (such as photovoltaics, wind power, hydrogen energy, energy storage, and new energy vehicles, etc.), stainless steel pipes have diverse application scenarios (such as fluid transportation, structural support, thermal management, etc.). The performance requirements for these pipes need to be determined comprehensively based on specific conditions (such as medium, pressure, temperature, environmental corrosion, etc.). The following are the common and specific domain core requirements: 

I. Core Material Performance Requirements

Corrosion Resistance

New energy equipment often comes into contact with corrosive media (such as electrolyte, coolant, hydrogen, moisture, salt fog, etc.), and it is necessary to select an appropriate stainless steel grade based on the characteristics of the medium:

General corrosive environment (such as air, fresh water): 304 stainless steel (containing 18% Cr and 8% Ni) can meet basic requirements;

Strong corrosive environment (such as electrolyte, seawater, trace impurities in hydrogen): 316L (containing Mo, enhancing resistance to pitting), duplex steel (such as 2205, balancing strength and corrosion resistance), or super austenitic stainless steel (such as 904L, resisting overall corrosion) are required;

Hydrogen energy field: It is necessary to resist hydrogen embrittlement and hydrogen permeation, and prioritize high-nickel austenitic stainless steel (such as 316Lmod), avoiding hydrogen-induced cracking (HIC) and stress corrosion cracking (SCC).

Mechanical Properties

It is necessary to achieve a balance of strength, toughness, and fatigue performance:

High-pressure scenarios (such as hydrogen energy storage and transmission pipelines, high-pressure container connection pipes): High tensile strength (≥500 MPa), high yield strength (≥200 MPa), and sufficient elongation rate (≥40%) are required to avoid brittle fracture;

Dynamic load scenarios (such as wind turbine tower pipe lines, new energy vehicle chassis pipe lines): Excellent fatigue strength (≥200 MPa after 10⁷ cycles) is required to resist vibration fatigue;

Low-temperature scenarios (such as low-temperature energy storage): Low-temperature impact toughness (-40°C, AKV ≥ 40 J) is required to prevent low-temperature fracture. 

II. Structural and Process Requirements

Dimensional Accuracy and Consistency

The pipe diameter and wall thickness tolerances must be strictly controlled (±0.1mm) to ensure the sealing performance (such as the fit with flanges and bushings);

Wall thickness uniformity (deviation ≤ 5%), to avoid local stress concentration leading to rupture (especially in high-pressure scenarios).

Surface Quality

Surface finish (Ra ≤ 1.6μm): reduce fluid resistance (such as in cooling pipelines), prevent pollutant adhesion (such as in photovoltaic cleaning systems);

Surface passivation treatment: through chromate passivation or acid washing, form a dense oxide film, enhancing corrosion resistance;

No surface defects (such as cracks, pinholes, scratches): avoid defects becoming the starting point of corrosion or stress concentration.

Welding and Connection Reliability

If it is a welded pipe, the weld seam must have no defects such as pores, slag inclusions, or incomplete fusion, and the weld strength should not be lower than the base material (need to pass flaw detection tests, such as X-ray, ultrasonic);

Appropriate connection method (welding, flange, bushing, etc.): for hydrogen energy pipelines, welding should avoid intergranular corrosion caused by high temperature, and necessary post-weld heat treatment should be carried out. 

III. Environmental and Operating Condition Adaptability

Thermal Resistance

High-temperature scenarios (such as photovoltaic-thermal power generation, fuel cell stacks): Must be resistant to high-temperature oxidation (such as 310S stainless steel, with a temperature resistance of up to 1100°C), and have a stable thermal expansion coefficient to avoid thermal stress cracking;

Low-temperature scenarios (such as liquid hydrogen storage and transportation, low-temperature energy storage): Must maintain low-temperature toughness (such as 304L, with good impact performance at -196°C), and prevent low-temperature fracture.

Resistance to Hydrogen Embrittlement and Hydrogen Permeation (Core in the Hydrogen Energy Field)

Under high-pressure hydrogen environments (35MPa/70MPa), hydrogen molecules are prone to penetrate the stainless steel lattice, causing embrittlement. Required:

Choose austenitic stainless steel with low hydrogen solubility (such as 316L), or apply surface coatings (such as diamond-like carbon DLC) to reduce hydrogen permeation;

Control the material hardness (≤240HV), avoiding an increase in hydrogen embrittlement sensitivity due to high hardness;

Verify through hydrogen embrittlement tests (such as ASTM F1459) to ensure no cracking risk within the design lifespan.

Fatigue and Vibration Resistance (such as wind power, new energy vehicles)

The internal pipelines of wind turbine towers need to withstand long-term vibration, requiring the material to have high fatigue strength (10⁷ cycle strength ≥ 150MPa);

The cooling pipes of new energy vehicle batteries need to withstand jolting vibration, with uniform pipe walls and no defects to avoid fatigue failure. 

IV. Compliance and Sustainability

Standards and Certifications

It is necessary to comply with specific industry standards, such as:

Hydrogen pipelines: ISO 19880 (Hydrogen Infrastructure), GB/T 37244 (High-Voltage Hydrogen System for Vehicles);

New energy vehicle pipelines: ISO 11439 (Stainless Steel Pipes for Road Vehicles);

Photovoltaic / Wind power: GB/T 14976 (Stainless Steel Pipes for Fluid Transportation), ASTM A312 (Austenitic Stainless Steel Seamless Pipes).

Low Carbon and Sustainability

The new energy industry emphasizes "low carbon throughout the entire life cycle", requiring the production process of stainless steel pipes to use green electricity for smelting (such as hydrogen-based steelmaking), and the materials to be recyclable (the stainless steel recycling rate is > 90%), in line with the requirements of the circular economy. 

V. Special Requirements for Specific Fields

Cooling pipelines for new energy vehicles: Need to be lightweight (thin wall ≤ 1mm but with high strength), resistant to corrosion from coolant (ethylene glycol), and compatible with connection components (such as plastics, rubber) without electrochemical corrosion;

Pipelines for photovoltaic cleaning systems: Resistant to ultraviolet aging, resistant to corrosion from cleaning solutions (weak acids and alkalis), and with smooth inner walls to reduce scale formation;

Pipelines for energy storage battery compartments: High fire resistance (such as meeting UL 94 V-0 standards), and resistant to electrolyte leakage (such as LiPF₆) corrosion. 

In conclusion, for the stainless steel pipes in the new energy industry, they must precisely match the working conditions in terms of core indicators such as corrosion resistance, mechanical properties, and environmental adaptability, and must also meet compliance and sustainability requirements. Different sub-sectors require targeted optimization designs.