Certificates and Standards for Gas Installation Components – What Every Part Must Have
Certificates and standards for gas installation components – what every part must have
When a customer enters a store or browses an e-shop looking for a ball valve or a gas flex hose, most of them ask only about two things: price and thread. Certificates and standards do not interest them – at least until the gas inspector stops the inspection or the insurance company refuses to pay the claim after an incident. From practice I know that gas installation components without proper certification are among the most common reasons why the inspection technician refuses to sign the acceptance protocol of the gas appliance into operation. This article therefore explains in detail what exactly every component of the gas installation must be certified for, which standards and marks to look for on the packaging or on the part itself, and where installers and households most commonly make mistakes when choosing.
Why certificates are more important for gas than for any other product
Gas is not water. A water leak is unpleasant and expensive, but a gas leak can be deadly. From this simple fact arises the entire legislative and standard architecture surrounding every part of the gas installation – from the smallest fitting to the main shut-off valve. The Slovak Republic is a member of the EU and has harmonized most of the technical regulations with the European space, so the primary decisive factors are European regulations and harmonized technical standards, above which stand national laws and decrees.
The basic legal framework is the Regulation of the European Parliament and of the Council (EU) 2016/426 on gas-burning appliances (GAR – Gas Appliances Regulation), which replaced the original directive 2009/142/ES as of April 21, 2018. This regulation, however, does not directly address accessories and components of gas installations in full – other regulations and harmonized standards EN apply to them. It is important to understand that certification of a component is not just a formality: it is proof that the product has passed a testing process by a notified body or has been subject to internal production control according to precisely defined procedures and meets defined parameters – maximum operating pressure, temperature range, leak resistance, material compatibility with gas.
CE mark – the basis, but not everything
The first thing a customer or installer should look at is the CE mark on the packaging or on the component itself. CE (Conformité Européenne) indicates that the manufacturer declares the product's conformity with the requirements of the relevant European directives and regulations. Without CE, the product must not be legally placed on the market in the EU. However – and this is the key point – CE by itself says nothing about whether the product was tested by an independent testing laboratory, or whether the manufacturer only declared conformity based on its own internal control.
For gas installation components, there are various conformity assessment modules. The highest level of reliability is modules B+C, B+D or B+E, in which a notified body (e.g. DVGW in Germany, TÜV, KIWA, BV) performs a type test and subsequently controls the production. For cheap products without a brand, modules A or A2 are common, where the manufacturer only prepares the technical documentation and declares conformity on their own. Both types carry the CE mark – the difference is in the degree of independent verification.
Practical conclusion: CE on the component is a necessary condition, but for gas products you should also look for additional certificates that confirm real independent testing.
Key harmonized EN standards for gas installation components
European technical standards for gas components are quite extensive, but for a typical household or apartment installation the following are decisive:
EN 331 – ball valves and shut-off valves for gas
Standard EN 331:2015+A1:2019 defines requirements for manually operated ball valves and shut-off valves made of metallic materials for gaseous fuels, intended for use in family homes, apartment buildings and small industrial applications, for pressures up to 5 bar (for some categories up to 0.5 bar). The standard covers sizes DN 10 to DN 150, temperatures from -20 °C to +60 °C and defines:
- leak tightness classes (Class A – leak-tight, Class B – minimum leak tightness)
- operating pressure: typical household valves are usually category MOP 0.5 bar or MOP 5 bar
- gas flow direction (unidirectional vs. bidirectional design)
- requirements for the handle turning torque
- anti-static design (grounding of the ball seal)
- leak resistance tests – pneumatic tests inside the body and in the valve seat
For example, the gas ball valve FF 2" with internal thread and lever must be certified exactly according to this standard – in this case for size DN 50, which is a large diameter typical for main risers or inlet to the boiler room. The customer must verify for such a valve whether the tightness class (Class A or B) and maximum operating pressure are stated.
EN 14800 – flexible hoses for connecting appliances
Standard EN 14800:2007+A1:2010 (currently undergoing revision) sets requirements for safety hoses for household gas appliances. It applies to hoses made of stainless steel with a corrugated inner tube, braided or non-braided, with fixed or rotating ends for family households, apartment units and small commercial premises. It defines:
- maximum operating pressure: typically 0.5 bar (50 mbar) for low pressure and 5 bar for medium pressure
- test pressure: usually 2× MOP (at least 3 bar)
- lengths and tolerances: standardly 100 cm, 150 cm, 200 cm and others
- mechanical resistance: bending tests, twisting tests
- resistance to UV radiation and aging
- anti-static properties
- marking (each hose must have a permanent inscription with the standard, MOP, date of manufacture or expiration date)
Specifically: connecting flexible hose for gas WS-CE R1/2(T)-G1/2 MF 150 cm carries the abbreviation "WS-CE" in the name, which refers to a specific manufacturer and CE certificate, while the overall certification must meet EN 14800. Similarly, Flexira xConnect Gas Standard R1/2(T)-G1/2, 2 000 mm is a longer version of the same category of products – and especially with long hoses (2 000 mm), it is particularly important that the certificate also covers the given length, as tests are carried out for specific length ranges.
EN 10226 / ISO 7-1 – thread standards
Although a thread standard is not a safety certificate in the true sense of the word, its compliance is critical for the tightness of the connection. Gas installation components must have cylindrical (Rp/R) or conical (NPT) threads manufactured to the tolerance specified in the standard. A combination of conical and cylindrical threads is acceptable for gas only when using sealing compound or approved hemp sealing material for gas. This issue is discussed in detail in the topic How to choose the right ball valve for gas – thread, material and sealing class in our Knowledge Centre.
Further relevant standards
- EN 549 – elastomeric materials for seals and membranes in gas equipment (rubber must be resistant to natural and liquefied gases)
- EN 751 – sealing compounds for metallic threaded joints in gas piping
- EN 1057 – copper pipes and fittings for gas installations
- EN 10255 / EN 10217 – steel pipes for gas piping systems
- STN EN 1775 – gas supply, gas piping in buildings (valid Slovak standard)
- STN 38 6405 – Slovak standard for gas equipment, safety principles
DVGW, KIWA, GASTEC QA and other independent certification schemes
In addition to the mandatory CE marking, there are national and international voluntary certificates that significantly increase the reliability of a component in practice. Inspection technicians and experienced fitters recognize and prefer them.
DVGW (Germany)
DVGW (Deutscher Verein des Gas- und Wasserfaches) is a German technical and scientific organization whose certification program is the de facto gold standard in the Central European region. A product with the DVGW logo has passed tests in an accredited DVGW laboratory and meets the relevant DVGW work sheets (e.g. VP 604 for flexible hoses, VP 614 for ball valves). In the Slovak and Czech markets, the DVGW certificate is common among reputable manufacturers and many inspection technicians require it for the certification of higher performance equipment.
KIWA (Netherlands / international)
KIWA is a Dutch certification organization with international reach. Its certificates are common especially among manufacturers of flexible hoses, fittings and pressure regulators. A KIWA certificate includes a type test and regular production checks.
GASTEC QA
The GASTEC QA (Quality Assurance) system is a certification scheme focused on gas installation products for households. It is widespread mainly in the Benelux and the United Kingdom, but products with this certificate are also sold in the Central European market.
IMQ (Italy)
Italian manufacturers of gas installation components (some of whom supply the Slovak market) often carry the IMQ certificate, which is the national Italian equivalent of DVGW.
What must be physically marked on the component and packaging
European standards and national legislation precisely define which data must be permanently marked on each gas installation component. The absence of any of these data is a sign that the product may not be certified or that the certificate is not valid for the given type. Check the following:
On ball valves and fittings
- CE mark (minimum 5 mm height)
- Name or trademark of the manufacturer
- Rated size (DN or inches)
- Maximum operating pressure (MOP) in bar
- Sealing class (Class A or B according to EN 331)
- Material designation of the body (brass/bronze/gunmetal, possibly stainless steel)
- Flow direction (if it is a one-way valve)
- Year of manufacture or batch number
- Number of the notified body (if involved) – e.g. 0036 for TÜV Rheinland
On flexible hoses
- Standard marking: EN 14800
- Type of gas (e.g. G20 – natural gas, G30 – propane-butane)
- MOP (maximum operating pressure), e.g. 0.05 MPa (= 0.5 bar)
- Total length of the hose in mm
- Date of manufacture (month and year) or expiry date – very important!
- Batch number
- CE mark and possibly the number of the notified body
- Name or brand of the manufacturer
Practical tip from the field: flexible hoses without an embossed date of manufacture directly on the hose body (not just on the cardboard packaging) are problematic for inspection, as cardboard is easily lost. The date must be on the metal body or on a permanent label.
Material requirements and their certification
Not every material suitable for water is suitable for gas. This is a classic mistake made by an inexperienced fitter – they install fittings or seals from a water installation into a gas line because they look the same visually. However, the difference can be crucial:
Brass (Brass/CW617N, CW602N)
The most common material for gas valves. It must be dezincification resistant – meaning it must be alloyed with lead and antimony content to prevent zinc leaching in contact with natural gas, which may contain moisture. Do not forget that brass corrosion products can clog compressor seats or regulators. CE certification according to EN 331 also tests material compatibility.
Rubber and elastomeric seals
Standard EN 549 defines requirements for elastomeric materials intended for gas equipment. Sealing rings and membranes must be resistant to natural gases (G20), LPG (G30/G31) and their mixtures. Common EPDM or NBR rubber from water installations may swell or harden in contact with LPG – this leads to gas leakage. This fact is discussed in more detail in the topic Sealing of gas connections – how to check for gas leaks yourself.
Corrugated stainless steel tube in flexible hoses
Must be made of austenitic stainless steel (typically AISI 304 or AISI 316). Certification according to EN 14800 tests resistance to cyclic bending, twisting and pressure. Low-quality hoses with thin-walled tubes may crack when bent incorrectly during installation – more on this in the topic What diameter and length of flexible hose for gas – how to measure and choose correctly.
Inspection Practice in Slovakia – What the Technician Checks
The gas equipment inspection technician (certified according to the decree of the Ministry of Transport, Construction and Regional Development of the Slovak Republic No. 508/2009 Coll.) assesses, among other things, the certification of used components during the technical inspection and testing of the gas equipment. In practice, it looks like this:
The technician visually inspects the valves, hoses, and fittings. He looks for the CE mark, the standard number, and the manufacturer's identification. If any mandatory marking is missing on the component, the technician has the right (and obligation) to note it as a defect in the report. In such a case, the investor will receive a period to correct the issue – replace the component with a certified one – before the equipment is put into operation.
The second thing the technician checks is the validity of flexible hoses. Flexible gas hoses have a limited lifespan – typically 10 years from the date of manufacture (some standards and manufacturers specify 5 or 8 years for LPG). After this period has elapsed, the hose is considered non-compliant regardless of its visual condition and must be replaced. The inspection technician therefore checks the date of manufacture directly on the hose, and if this information is unreadable or missing, the hose is automatically considered non-compliant. The topic of hose replacement is discussed in detail in the article Replacement of a flexible gas hose – how to recognize when it is time to replace it.
The third area of inspection is pressure testing. The inspection technician performs a pressure test on the entire piping system and checks the tightness of each connection. Even if all components are certified, poor installation (e.g., inappropriate sealing, insufficient thread sealing, incorrectly inserted hose end) can lead to the test failing. This is discussed in the topics Installation of a ball valve for gas – procedure, tools, and safety rules and Connecting an appliance via a flexible gas hose – step by step.
Most Common Errors in Component Selection from the Perspective of Certification
Over the years of working with gas installation products, we have seen dozens of situations where the customer or installer purchased an unsuitable component. The most common scenarios:
1. Confusing Gas and Water Installation Components
Visually, ball valves for water and gas are almost identical. The difference lies in the sealing material (NBR resistant to gaseous hydrocarbons vs. EPDM for water), in the sealing class (a gas valve must meet Class A according to EN 331, while a water installation valve does not necessarily guarantee this), and in the marking. An installer who is unsure should always look for the explicit marking "GAS" or "für Gas/for Gas" directly on the body of the valve. Comparing valve types is also discussed in the topic Ball valve vs. other types of gas shut-off valves – when to use which.
2. Using an Expired Hose from Stock
Construction companies or maintenance personnel sometimes reach for a hose that has been lying in the warehouse for several years. If it was manufactured more than 10 years ago, it is automatically non-compliant – regardless of how it looks. The date of manufacture is a mandatory piece of information and the inspection will check it.
3. Hoses without Markings or with Unreadable Markings
Cheap hoses from markets or dubious e-shops may have the marking only on a label that can peel off. Or the standard numbers are so small that they are unreadable. The inspection technician may reject such a component as unidentifiable.
4. Inappropriate Combination of Threads with Unsuitable Sealing
The use of Teflon tape (PTFE) is conditionally acceptable for gas, but not all types are certified for gas connections. The EN 751 standard defines which sealing materials are approved for gas threaded connections. For example, hemp sealing must be impregnated with a paste approved for gas (not a water-approved linseed paste). This topic is discussed in detail in the article Common mistakes in the installation of gas installation components and how to avoid them.
5. MOP of the Component Does Not Match the Operating Pressure of the Network
Medium-pressure gas piping systems operate at pressures up to 0.5 bar, some industrial ones at 4 bar. A component with an MOP of 0.5 bar must not be used after the pressure regulator if the pressure after it is medium. This is checked during the inspection by comparing the design documentation and component markings.
How the Customer Can Verify Product Certification Before Purchase
A few practical tips for anyone purchasing gas installation components:
- Request a Declaration of Conformity (DoC): Every manufacturer is required to have a written Declaration of Conformity available. A reputable seller/manufacturer can provide it in PDF format.
- Check the physical marking: The standard, CE, MOP, and date of manufacture – these data must be on the product, not just on the packaging.
- Verify the notified body number: The number after CE (e.g., CE 0036) can be looked up in the NANDO (New Approach Notified and Designated Organisations) database on the European Commission's website. There you can see who and for which products is notified.
- Look for a product datasheet with technical parameters: A reputable manufacturer always provides a technical datasheet with listed standards, pressures, temperature ranges, and materials.
- Be cautious of extremely low prices: Certification of a component takes time and money. If the price is suspiciously low, the certification is likely not in order.
Lifespan, inspection intervals and documentation archiving
Component certification is relevant not only during the initial installation but also during regular inspections. According to Decree No. 508/2009 Coll. and STN EN 1775, gas appliances in residential buildings must be inspected regularly – typically every 3 years in household installations, and according to the project documentation in industrial settings. During each such inspection, the technician will again check the condition and validity of the components.
The owner or building manager should archive:
- Project documentation of the gas installation
- Reports from professional inspections and tests
- Statements of conformity (DoC) for key components – valves, hoses, regulators
- Invoices and delivery notes with component identification (batch number, delivery date)
These documents are crucial in the case of an incident. The insurance company will investigate during a claim whether the installation was carried out with certified components and whether the inspection intervals were followed. Without documentation, the claim may be rejected or reduced.
Frequently asked questions (FAQ)
Is it possible to use a ball valve for water also for gas, if it has the same threads?
No. Even if the threads are the same, a water installation valve may not have EN 331 certification for gas, may have an unsuitable sealing material (EPDM instead of NBR) and may not meet the tightness class requirements for gaseous media. The inspection technician will detect and reject it. Always use valves with an explicit marking for gas and EN 331 certification.
How many years is a flexible gas hose valid for?
Standardly 10 years from the date of manufacture for natural gas; some manufacturers specify a shorter period for LPG (propane-butane), usually 5 years. The date of manufacture must be engraved directly on the metal body of the hose. After this period has expired, the hose must be replaced regardless of its visual condition. Never use it if the date is unreadable – this is in itself a reason for replacement.
What does "MOP 0.5 bar" on a ball valve or hose mean?
MOP (Maximum Operating Pressure – maximum operating pressure) 0.5 bar means that the component is certified for continuous use at a pressure up to 0.5 bar (500 mbar). Most household low-pressure gas distribution systems behind the regulator operate at a pressure of 20–25 mbar, which is significantly lower. A component with MOP 0.5 bar is generally sufficient for household distribution. For medium-pressure distribution before the household regulator, components with MOP 4 bar or 5 bar and the appropriate certification are required.
Do I need to have a statement of conformity physically available for each component during an inspection?
The inspection technician usually checks the physical marking directly on the components – CE, standard, manufacturer, MOP. You are not necessarily required to have the statement of conformity (DoC) on hand during the inspection, but you should be able to present it in a reasonable time in case of doubts. For larger equipment, boiler rooms and commercial operations, the inspection technician will require the DoC as part of the equipment documentation. For a standard household installation, it is advisable to store the DoC together with other property documentation.
Can I replace a flexible gas hose myself and is it legal?
Replacing a flexible gas hose yourself is a grey area in Slovak legislation – the law does not explicitly state that only a qualified person can perform a household installation, but a professional inspection after the replacement is mandatory. In practice: if you replace the hose yourself, your choice of a certified component is key, as the inspection technician will check it during the next inspection. Regardless, after replacing any hose or valve, we recommend a tightness test, described in the topic Gas connection tightness – how to check for gas leaks yourself.
What is the difference between "Class A" and "Class B" according to EN 331 for gas ball valves?
Class A (class A) means that the valve is completely leak-tight in the closed position – no measurable amount of gas can pass through the closure. This is a requirement for main shut-off valves in household gas installations. Class B (class B) allows for minimal leakage tightness, which is acceptable, for example, in industrial applications with continuous monitoring. For standard residential and single-family homes, a Class A valve should always be used.
Conclusion
Certification of gas installation components is not a bureaucratic burden – it is a system that genuinely protects lives and property. Every part of the gas distribution system, from the smallest fitting to a large ball valve FF 2" with lever, must not only be technically correctly selected and installed, but also properly certified according to the relevant European standards. Flexible hoses, such as connecting flexible hose WS-CE 150 cm or Flexira xConnect Gas Standard 2 000 mm, must be certified according to EN 14800 and must have all required information clearly marked on the metal body, including the date of manufacture.
Investing in certified components from verified manufacturers always pays off – not only in terms of a successful inspection, but above all in terms of long-term safety. Gas does not tolerate experiments with unknown components. If you are unsure about the selection of a particular product, check other topics in the Knowledge Centre, where you will find detailed guides on selection, installation and verification of the tightness of the entire gas installation.
Do you have a question about this topic?
Are you unsure or dealing with a specific situation in your household? Write to us – we are happy to help.