Author: Beijing Guojie Pipeline Co., Ltd.
Abstract: New energy projects cover multiple scenarios such as hydrogen energy, electrochemical energy storage, photovoltaic high-purity media, and onshore wind power cooling, and their media characteristics, safety risks, and cleanliness requirements are significantly different from those of traditional chemical and thermal power pipelines.Direct substitution with general pressure pipeline fittings can easily lead to hidden hazards such as hydrogen embrittlement leakage, electrolyte corrosion, high-purity media contamination, and low-temperature brittle fracture.This paper reviews the regulatory framework for new energy pipelines, classifies special procurement requirements by scenario, including material compatibility, cleanliness control, explosion-proof and anti-static measures, low-temperature and high-pressure service, and prefabricated supporting components, clarifies key control points for supplier admission, technical agreements, inspection and testing, and documentation traceability, and establishes a fitting procurement control system suitable for the new energy industry.
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I. Introduction
With the rapid development of the new energy industry, projects such as hydrogen production, storage, and refueling, electrochemical energy storage, photovoltaic high-purity processes, and wind power cooling systems are equipped with large numbers of pressure pipeline fittings.Compared with traditional petrochemical and thermal power projects, the operating conditions of new energy pipelines are highly differentiated: high-pressure gaseous hydrogen and low-temperature liquid hydrogen carry the risk of hydrogen embrittlement failure;Energy storage liquid cooling and electrolyte pipelines face electrochemical corrosion and alternating temperature loads;Photovoltaic semiconductor high-purity pipelines have stringent requirements for inner wall cleanliness and precipitation control;Prefabricated cabins and containerized energy storage have compact internal spaces, imposing special constraints on pipe fitting geometry, flow resistance, lightweight design, and integrated prefabrication.
In actual project procurement practice, many procurement personnel follow conventional industrial pipeline procurement experience, simply selecting by PN pressure rating and DN size, and directly using ordinary GB/T12459 pipe fittings for hydrogen energy and energy storage systems, ignoring special indicators such as material-media compatibility, micro-leakage control, anti-static and explosion-proof requirements, inner wall degreasing and passivation, and low-temperature toughness, which leads to leakage during pressure testing, cracking during long-term operation, and contamination of high-purity media by impurities, causing project shutdowns, safety hazards, and huge rework losses.Procurement of new energy pipeline fittings is not a simple selection of general-purpose fittings, but scenario-based specialized procurement management based on media risks, safety specifications, and project process characteristics.
II. Applicable Standard Systems and Scenario Classification for New Energy Pipeline Fittings
The standard system for new energy pipeline fittings is characterized by the parallel existence of national standards, group standards, and American standards, with obvious differences in implementation specifications across different sub-sectors.In the hydrogen energy field, the core implementation standards are GB 50177 Design Code for Hydrogen Stations, T/CAS Technical Specification for Hydrogen Transportation Pipelines, and ASME B31.12 Hydrogen Piping Code, which impose mandatory constraints on material hydrogen compatibility, hydrogen embrittlement testing, and micro-leakage detection;Electrochemical energy storage liquid cooling pipelines refer to the GB/T20801 pressure piping code and local and group standards for prefabricated energy storage cabins, with emphasis on resistance to glycol coolant corrosion and long-term sealing reliability;Photovoltaic high-purity fluid pipelines implement the relevant standards for semiconductor high-purity piping, controlling inner wall roughness, precipitates, and grease residue;Liquid hydrogen projects additionally apply low-temperature pressure-bearing standards, assessing the low-temperature impact toughness of materials to prevent low-temperature brittle fracture failure.
According to risk level, new energy pipelines can be divided into two major categories: high-risk medium pipelines and general auxiliary pipelines.High-risk pipelines include high-pressure hydrogen pipelines at hydrogen refueling stations, liquid hydrogen transport pipelines, and energy storage electrolyte transport pipelines, which are key regulatory targets;General pipelines are energy storage air cooling pipelines, photovoltaic circulating cooling water, and wind power cooling pipelines, with relatively lower risk, but they still cannot directly copy municipal or ordinary chemical procurement standards.The primary task in the early procurement stage is to lock down the project's specific segment, medium type, and pressure and temperature range, and determine the applicable standard version as the prerequisite basis for preparing the technical agreement, avoiding standard mismatch.
III. Special Requirements for Material Selection and Medium Compatibility of New Energy Pipe Fittings
Material compatibility is the primary control point in new energy procurement, and also the most core special requirement that distinguishes it from conventional pipeline procurement.In hydrogen energy scenarios, ordinary high-strength carbon steel is prone to hydrogen-induced cracking and hydrogen embrittlement in high-pressure hydrogen environments. Not all stainless steels are suitable for high-pressure hydrogen working conditions. 316L and 304L austenitic stainless steels are the mainstream choices for hydrogen energy projects. Some high-pressure and liquid hydrogen working conditions require supporting hydrogen compatibility test reports, strictly controlling material inclusions and harmful element content, and reducing hydrogen embrittlement sensitivity. Ordinary WCB cast steel pipe fittings are not allowed to be directly selected for high-pressure hydrogen systems.
The medium in electrochemical energy storage liquid cooling pipelines is mostly ethylene glycol aqueous solution. Under long-term circulation conditions, there are risks of chloride ion enrichment and electrochemical corrosion. 316L austenitic stainless steel is preferred, with strict control of carbon content to avoid intergranular corrosion;Electrolyte pipelines contact acid and alkali media, and some working conditions require duplex stainless steel or plastic-lined and fluorine-lined supporting solutions.For photovoltaic high-purity pipelines, the inner walls of pipe fittings need electrolytic polishing EP treatment, with controlled Ra roughness and strict degreasing and oil removal to prevent metal ions and organic matter from precipitating and contaminating high-purity process media. Ordinary acid-pickled pipe fittings cannot meet the acceptance requirements for high-purity scenarios.Liquid hydrogen pipelines are in a -196°C ultra-low temperature environment for a long time. Materials must meet low-temperature impact test requirements, and materials that undergo phase transformation or sharp toughness reduction at low temperatures are prohibited. Welds also require supporting low-temperature assessment.
In new energy projects, arbitrary material substitution across scenarios is strictly prohibited. Any material change must undergo process and design review, and when necessary, supplementary compatibility, aging, and fatigue verification must be added to form written substitution approval documents. Suppliers and procurement departments have no right to replace grades on their own.
IV. Special procurement constraints for sealing, explosion-proof and anti-static, and clean degreasing
Conventional industrial pipeline procurement focuses on controlled wall thickness, dimensions, and hydrostatic testing;New energy pipe fittings add mandatory additional requirements such as micro-leakage, anti-static, degreasing and passivation, and clean packaging.Hydrogen energy involves flammable and explosive media; hydrogen molecules are small in volume and highly permeable. Flanges and pipe fitting joints cannot rely solely on macroscopic hydrostatic testing. Procurement technical agreements must specify micro-leakage detection requirements, conduct fugitive emission testing in accordance with ISO15848, and control helium leak detection rate indicators to reduce the risk of hydrogen accumulation and explosion.
For pipeline systems in hydrogen energy and energy storage battery areas, pipe fittings, flanges, matching gaskets, and fasteners must meet anti-static conductivity requirements, control surface resistance, and be equipped with grounding structures to eliminate the risk of ignition caused by static electricity accumulation;Non-metallic seals matched with pipelines must be provided with medium aging resistance test reports, and must not swell or become brittle under long-term immersion in hydrogen and coolant environments.High-purity photovoltaic pipe fittings must undergo strict degreasing, acid pickling, electrolytic polishing, and high-purity nitrogen purging before leaving the factory. Both ends of the pipe fittings must be sealed with dust-proof sealing plugs and packaged in clean bags. Factory documents must include clean processing records and grease residue detection reports. Ordinary pipe fittings' anti-rust oil and anti-rust paper are not allowed for high-purity pipeline supply to prevent secondary contamination.
The interior space of energy storage prefabricated cabins is narrow and equipment-dense, so pipe fitting selection must also take into account low flow resistance and compact structure. Thin-wall precision-formed pipe fittings should be prioritized to reduce on-site welding workload and adapt to modular prefabricated assembly requirements. This is also a procurement demand unique to new energy energy storage projects.
V. Differentiated Requirements for Supplier Admission, Process Qualification, and Inspection and Testing
The entry threshold for new energy pipe fitting suppliers is higher than that for ordinary pressure piping. In addition to the special equipment pressure piping component manufacturing license, the project performance and specialized testing capabilities in the corresponding track must be verified.Hydrogen energy pipe fitting suppliers should have supporting conditions for hydrogen compatibility specimen testing, helium leak testing, and low-temperature testing;High-purity pipeline suppliers need to have independent cleanrooms and EP polishing production lines;Energy storage liquid cooling pipe fitting suppliers need stable stainless steel forming and solution heat treatment capabilities.Before a new supplier is included in the list, a source-site audit must be carried out to verify the scope of process qualification, with a focus on checking whether the welding WPS/PQR covers new energy operating conditions. Welding qualification for hydrogen energy and low-temperature pipelines needs to add hydrogen embrittlement and low-temperature impact assessment items, and cannot directly reuse room-temperature chemical welding qualification.
Inspection and testing are subject to tiered and differentiated control.For high-pressure hydrogen and liquid hydrogen pipe fittings, 100% non-destructive testing of welds is required, along with hydrostatic pressure testing and helium leak detection;Energy storage liquid cooling pipe fittings are subject to batch sampling for non-destructive testing and sealing tests;For high-purity piping, check the inner wall appearance, roughness, and cleanliness records piece by piece.In addition to the conventional specifications, heat numbers, and materials, the factory steel stamp markings need to indicate the applicable medium and special treatment status (EP polishing, degreasing, dedicated for hydrogen service), so as to facilitate distinction during on-site acceptance and prevent fittings for different scenarios from being mixed up.
VI. Technical Agreements, Incoming Acceptance, and Closed-Loop Document Management
Procurement contracts and technical agreements for new energy projects must separately add dedicated clauses; this is the key to implementation of control.In addition to conventional dimensions, wall thickness, and standards, the agreement shall specify medium compatibility requirements, cleanliness treatment grade, degreasing and passivation specifications, helium leak detection rate indicators, anti-static requirements, low-temperature impact, packaging and protection methods, and the document delivery list.For high-risk piping in hydrogen energy and energy storage, agree on hold points for inspection, and when necessary arrange source surveillance to witness non-destructive testing and sealing tests.
Incoming acceptance shall follow the process of "documents first, physical verification second"; in addition to material MTRs, non-destructive reports, and hydrostatic test records, collect hydrogen compatibility reports, cleanliness testing, helium leak detection reports, low-temperature impact reports, and passivation and degreasing records as needed.Fittings with missing documents or incomplete special test reports shall be rejected directly and must not be put into storage for use.All furnace batch numbers, inspection records, and processing records correspond one-to-one, enabling full-chain traceability for each individual piece and meeting the archiving requirements for safety reviews, power grid acceptance, and safety supervision spot checks of new energy projects.
VII. High-Frequency Risks and Prevention and Control Strategies in Procurement of Pipes and Fittings for New Energy
High-frequency procurement risks in the industry are concentrated in six categories: First, confusing general-purpose pipe fittings with special-purpose pipe fittings for new energy, and directly using ordinary stainless steel pipe fittings for high-pressure hydrogen and high-purity pipelines;Second, the technical agreement lacks special clauses on medium compatibility, cleanliness, and micro-leakage, and the supplier produces according to ordinary products;Third, ignoring the risks of hydrogen embrittlement and low-temperature brittle fracture, resulting in incorrect material selection;Fourth, packaging and sealing are not standardized, causing secondary contamination of high-purity pipe fittings during transportation and storage;Fifth, only hydrostatic pressure testing is performed, without helium micro-leakage detection, leaving hidden leakage hazards under hydrogen working conditions;Sixth, the supplier's performance record is falsified, and it lacks the supporting test capability for new energy working conditions.
Corresponding prevention and control strategy: establish a template for classified procurement lists of new energy pipe fittings, and set fixed technical clauses according to hydrogen energy, energy storage, photovoltaic high-purity, and low-temperature scenarios;Implement a supplier-specific performance verification mechanism, and establish a qualified supplier database by segment;Pre-review the complete set of documents and test reports before delivery to identify defects in advance;Store in partitioned warehouse areas, with high-purity pipe fittings and hydrogen pipe fittings stored separately to avoid mixed storage and misuse with ordinary pipe fittings;Conduct three-party technical briefings among procurement, supervision, and construction to clarify the identification and differentiation rules for pipe fittings of different pipelines.
VIII. Conclusion
The core feature of procurement for new energy pipeline fittings is that medium risk takes priority over pressure rating; special indicators such as compatibility, cleanliness, micro-leakage, and low-temperature toughness are often more critical than nominal pressure and dimensional specifications.Traditional chemical pipeline procurement centers on pressure-bearing capacity and dimensional matching, whereas new energy projects superimpose multiple risks including hydrogen embrittlement, explosion, electrochemical corrosion, high-purity contamination, and low-temperature failure.Procurement management needs to move beyond the general mindset of pipe fitting selection and establish differentiated procurement standards according to different scenarios such as hydrogen energy, energy storage, photovoltaics, and liquid hydrogen. It should integrate supplier specialized capability assessment, material compatibility verification, special inspection of cleanliness and sealing, and traceability of complete documentation throughout the entire procurement process, so as to avoid pipeline failure risks from the source, match the compliance requirements of safety acceptance and grid-connected commissioning of new energy projects, and support the safe and stable development of the new energy industry.
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