Membrane technology
Membrane housings are the pressure-resistant heart of every hydrogen membrane system. WOLF manufactures the diffusion-tight pressure housings that protect sensitive separation membranes and make their separation performance possible in the first place. Precision-machined and tested in accordance with AD 2000, EN 13445, and ASME. Upon request, we supply the complete skid from our own production facilities.
Pressure housings for sensitive separation membranes
Separation membranes are sensitive to mechanical stress and even very small leaks. We manufacture the pressure housings from carbon steel or stainless steel and tailor the surface finish as well as the geometry of the sealing and module mounts to the membrane system. This ensures that the membrane elements are securely held in place even at high operating pressures, and the intended separation process remains reliable.
Membrane housings in detail
A membrane housing protects the sensitive separation membranes while ensuring the clean fluidic separation of feed, permeate, and retentate. The following sections illustrate what a pressure housing must be capable of and how we manufacture it.
Requirements for a membrane housing
A membrane casing, also known as a pressure casing or membrane module casing, is a pressure-resistant vessel that houses one or more membrane modules. In conventional hydrogen plants, a stainless steel or carbon steel casing bundles several thousand polymer hollow fibers. During separation, the small H₂ molecule selectively passes through the membrane, while the larger residual gases—such as CH₄, CO₂, N₂, and O₂—remain behind. For this principle to function reliably over the long term, the housing must meet two requirements: high pressure resistance and leak-tightness down to the molecular level.
Everything from a single source: the complete membrane housing skid
We not only manufacture individual housings but, if required, the complete membrane skid. Depending on the project, we mount several hundred membrane housings on a steel frame and integrate the high-pressure piping as well as the necessary sensor systems. The assemblies are tested as a complete system and documented in a single set of documents.
In-house quality assurance (QA)
Quality assurance (QA) is handled by an in-house team of certified inspectors, utilizing a broad range of non-destructive and destructive testing methods, precise 3D measurement, and complete batch traceability. This ensures that every component meets our quality standards and applicable regulations. A dedicated team ensures seamless, audit-proof documentation; all materials, components, and filler metals are stored in a traceable and audit-proof manner.
Design in accordance with standards
We design pressure vessels in accordance with AD 2000 and EN 13445 using Sant’Ambrogio NextGen 2025, and in accordance with ASME Code Section VIII Div. 1 and Div. 2 using Compress 2025, supplemented by Dimy6. We perform FEM and CFD calculations using ANSYS Mechanical and Fluent 2025 R1, and nozzle structural analysis using Nozzle-Pro 15. Flange design in accordance with EN 1591-1 is performed using TEMESfcal, and the design is carried out in PTC Creo.
Diffusion-tight down to the molecular level
For hydrogen applications, we verify the required leak tightness using helium leak testing and document the achieved leak rates. Pressurized weld seams are tested non-destructively in accordance with the test specification. The pressure test is performed in accordance with EN 13445-5 using the specified test pressure.
Carbon, stainless, and duplex steels
Carbon steels: P265GH, P355GH, P355NH, P355NL1, 16Mo3, 13CrMo4-5, 10CrMo9-10, 15NiCuMoNb5-6-4, SA-516 Gr. 60/70, SA-350 LF2, SA-387 Gr. 11.
Stainless steels: 1.4301, 1.4541, 1.4571, 1.4539, SA-240, 304/321/316Ti/904L.
Duplex: 1.4462, SA-240, 318LN.
Clad versions, as well as Alloy 625 and Hardox, are available upon request.
Certificates and Approvals
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At WOLF Vessel and Apparatus Manufacturing, you and your projects are our top priority. You can always rely on our consistently high product quality and our comprehensive service.
Details on casings for membrane technology
What surface finishes do we achieve on the interior of our pressure housings? How do we design closures for quick membrane replacement? Here, we answer the most important technical questions about pressure housings for membrane systems.
How do you ensure the diffusion tightness of your housings? + − We employ a multi-stage inspection regimen: 100% visual testing (VT) and 100% radiographic or ultrasonic testing (RT/UT) of all pressure-bearing weld seams, in addition to helium leak testing with leak rates below 1 × 10⁻⁹ mbar·l/s at the sealing surfaces and a pressure test at 1.43 times the design pressure in accordance with EN 13445-5. For weld seams with a wall thickness of 30 mm or greater, we can include TOFD and phased array testing upon request.
We employ a multi-stage inspection regimen: 100% visual testing (VT) and 100% radiographic or ultrasonic testing (RT/UT) of all pressure-bearing weld seams, in addition to helium leak testing with leak rates below 1 × 10⁻⁹ mbar·l/s at the sealing surfaces and a pressure test at 1.43 times the design pressure in accordance with EN 13445-5. For weld seams with a wall thickness of 30 mm or greater, we can include TOFD and phased array testing upon request.
How do you handle high operating temperatures, such as those encountered with metal diaphragms? + − For membrane applications with operating temperatures above 400 °C—such as palladium metal membranes—we perform thermomechanical FEM simulations using ANSYS. Depending on the temperature level, we select heat-resistant steels such as 16Mo3 and 13CrMo4-5 or austenitic stainless steels and perform the creep strength analysis in accordance with EN 13445-3, Section 19. In the case of highly fluctuating load cycles, a fatigue analysis in accordance with EN 13445-3, Section 17 (simplified) or Section 18 (detailed), is also performed.
For membrane applications with operating temperatures above 400 °C—such as palladium metal membranes—we perform thermomechanical FEM simulations using ANSYS. Depending on the temperature level, we select heat-resistant steels such as 16Mo3 and 13CrMo4-5 or austenitic stainless steels and perform the creep strength analysis in accordance with EN 13445-3, Section 19. In the case of highly fluctuating load cycles, a fatigue analysis in accordance with EN 13445-3, Section 17 (simplified) or Section 18 (detailed), is also performed.
What are the advantages of complete in-house manufacturing of the skid? + − Conventional skid projects distribute vessels, piping, and steel fabrication among three suppliers. At WOLF, everything is produced under one roof. For you, this means:
- A consistent WPS/PQR strategy across all welded joints, eliminating the risk of interface issues
- Identical NDT depth on the housing and piping, verified by a Level 3 inspector
- a single set of documents for the entire skid instead of multiple files from subcontractors
- Helium leak detection and pressure test on the complete skid prior to shipment
- Clear accountability for warranty issues
Conventional skid projects distribute vessels, piping, and steel fabrication among three suppliers. At WOLF, everything is produced under one roof. For you, this means:
- A consistent WPS/PQR strategy across all welded joints, eliminating the risk of interface issues
- Identical NDT depth on the housing and piping, verified by a Level 3 inspector
- a single set of documents for the entire skid instead of multiple files from subcontractors
- Helium leak detection and pressure test on the complete skid prior to shipment
- Clear accountability for warranty issues
Can you also manufacture large membrane housing skids for industrial plants? + − Yes, that’s exactly what we’re equipped to handle. Individual membrane housings are relatively slim tubular components, typically ranging from 5 to 16 inches in inner diameter and up to about 10 meters in length. We deliver the decisive added value at the skid level: several hundred housings on a large, ready-to-install skid, complete with steel structure and operating platforms as well as full high-pressure piping, tested and documented as a complete package. We manufacture such skids for large-scale projects in the hydrogen industry.
Yes, that’s exactly what we’re equipped to handle. Individual membrane housings are relatively slim tubular components, typically ranging from 5 to 16 inches in inner diameter and up to about 10 meters in length. We deliver the decisive added value at the skid level: several hundred housings on a large, ready-to-install skid, complete with steel structure and operating platforms as well as full high-pressure piping, tested and documented as a complete package. We manufacture such skids for large-scale projects in the hydrogen industry.