BLUESEAL ULTRA 350 —
the gasket chosen for the medium, not the face
Gas-documented service. Oxygen-documented service. Chemicals. Oils. Fuels. High temperature. These are the applications where cellulose is not enough and the decision moves to aramid fibre. BLUESEAL ULTRA 350 is usually the first aramid-based material considered when the medium, temperature or approval requirement rules out cellulose.
Selection rule: BLUESEAL is selected for the medium, approval or higher thermal duty — not to hide a poor face.
Use this when: gas-documented duties, tougher chemical service, oxygen-documented applications, higher temperatures and industrial work that rules out cellulose.
Do not use this when: do not use it as a repair for a damaged, worn or uneven mating face. That is a face problem, not a medium problem.
Move away from BLUESEAL when: the face itself is the limitation, move toward FLEXSEAL; when steam or thermal cycling dominates, check GRAPHITESEAL.
What it is
BLUESEAL ULTRA 350
BLUESEAL ULTRA 350 is a general-purpose aramid fibre gasket material with inorganic fillers and NBR binder. The aramid fibre base gives the material excellent chemical stability, high mechanical strength and resistance to creep — the tendency of a compressed gasket to slowly yield under sustained temperature and pressure, losing clamping force over time.
Where a cellulose gasket like GREENSEAL PRO 180 is the right answer for standard water and heating service, BLUESEAL is usually the first aramid-based option to assess when the medium changes the specification — gas, chemicals, oxygen, oils, fuels, or temperatures above what cellulose can sustain reliably.
The number that defines it: 27 MPa residual stress at 175°C / 16h. Most gaskets lose significant clamping force under sustained heat. BLUESEAL retains 27 MPa after 16 hours at 175°C — and 23 MPa at 300°C. That is the technical reason it holds where cellulose creeps. The joint is more likely to retain sealing load under the conditions that ruled out cellulose.
Why aramid — and why it matters for your application
Aramid fibre is a synthetic fibre with exceptional tensile strength and thermal stability. In a gasket matrix, aramid fibres create a stiffer, more dimensionally stable material than cellulose — one that resists deformation under sustained load and temperature.
The practical consequence is lower creep relaxation. Above roughly 120 to 140°C continuous, a cellulose gasket begins to yield under sustained load — the bolt load drops, the contact pressure drops, the seal weakens over weeks and months. An aramid gasket under the same conditions is more likely to retain usable sealing load over time, which is why the specification moves away from cellulose as temperature and service life demands increase.
BLUESEAL — aramid
- Lower creep under sustained temperature
- Higher tensile strength — 12 MPa
- Stable across a wider chemical range
- Retains 23 MPa residual stress at 300°C
- Rated to 350°C peak, 250°C continuous
- BAM documentation for oxygen service
- DVGW, WRAS, SVGW, ABS, DNV
GREENSEAL — cellulose
- Higher compressibility — 9% vs 11%
- Better for low bolt load standard fittings
- FDA and KTW for food and drinking water
- Rated to 180°C peak, 140°C continuous
- Standard heating and water service
- Lower cost for everyday applications
- Not for gas, chemicals or high temperature
The approvals — what each one actually means
BAM
Oxygen-service documentation — the most demanding gasket certification. BAM tests for compatibility with pure oxygen under pressure, where most organic materials are a fire risk. BLUESEAL carries BAM documentation for oxygen-service applications.
DVGW
German gas approval — covers both the material standard (DIN 30653 HTB) and the specific leak rate test (DIN 3535-6) for gas service. A key gas-service approval reference for German-market installations and related specification environments.
WRAS
UK potable water approval. Required for any gasket material in contact with drinking water in UK installations. WRAS is the potable water signal for the UK market. DVGW and SVGW are the gas-side approvals referenced separately. BLUESEAL carries both categories, depending on the specific application.
SVGW
Swiss gas approval — equivalent to DVGW for the Swiss market. Relevant for gas installations in Switzerland and markets that reference Swiss standards.
ABS
Marine approval from one of the major international classification societies. Required for gasket materials used in marine vessel systems — pipework, engine rooms, auxiliary systems.
DNV
Marine and offshore approval from one of the leading classification societies. DNV covers marine, offshore oil and gas and related industrial applications where third-party material certification is required.
EC 1935/2004 food contact compliance is also confirmed — BLUESEAL meets the European regulation for materials in contact with foodstuffs, covering food processing and beverage industry applications.
Who uses it — and why
Gas installers and engineers
DVGW approval covers gas service in German-market installations. SVGW covers Switzerland. WRAS is a separate potable water approval for the UK market — it is not a gas signal, but BLUESEAL carries both, making it a relevant option where either medium is part of the specification and the corresponding approval framework applies.
Chemical and petrochemical industry
Resistance to oils, fuels, solvents and a wide chemical range makes BLUESEAL a relevant option for standard aramid-grade duty for chemical plant flanges where cellulose would swell, degrade or fail under the medium.
Marine and offshore
ABS and DNV approvals make the material relevant where marine classification documentation is required by the project specification. Used on vessel pipework, engine room systems and offshore equipment where third-party material certification is required by the build specification.
High-temperature industrial
Heat exchangers, steam systems and high-temperature process piping above 140°C — where cellulose is operating at or beyond its continuous limit and aramid's lower creep relaxation is one of the reasons the joint is more likely to retain sealing load over the service life.
BLUESEAL vs GREENSEAL — the practical distinction
BLUESEAL is chosen because of the medium. GREENSEAL is chosen because the medium is not the challenge.
Standard domestic and commercial heating at normal temperatures, water service, glycol circuits — GREENSEAL usually covers those applications adequately at a lower material specification level. The moment the medium changes — gas, oxygen, chemicals, high temperature above 140°C continuous — BLUESEAL is usually where the specification moves next.
Field example: Standard radiator valve union on a 75°C heating system — GREENSEAL. Gas meter union on a natural gas installation — BLUESEAL. Heat exchanger connection at 160°C continuous — BLUESEAL. Boiler primary union on a standard condensing boiler — GREENSEAL. The temperature and the medium decide, not the fitting type.
When to use it — and when not to
Where BLUESEAL makes sense
- The application is gas service — DVGW or SVGW required
- Oxygen service — BAM report scope required and checked
- Temperature above 140°C continuous
- Chemical service — oils, fuels, solvents
- Marine or offshore — ABS or DNV required
- High-pressure industrial flanges with good face condition
- Long service intervals where creep relaxation must be minimised
- Any application where chemical resistance to the specific medium is the deciding factor
- Clean, sound faces where the medium or approval is the primary challenge — not the face condition
When BLUESEAL is not the first answer
- Standard heating and water service at normal temperatures — GREENSEAL is usually the simpler and lower-spec option for standard-duty service
- The face is worn or uneven and compressibility is the main challenge — FLEXSEAL PRO 350 is the better answer
- Low bolt load fittings where a stiffer gasket requires more force than the joint can safely take
- The medium is standard potable water and no gas or chemical approval is required
Practical notes
Both faces carry anti-stick treatment. At the next service interval, BLUESEAL lifts away from the flange cleanly — less bonded residue, less face damage risk during removal, faster preparation for the replacement gasket. The face still needs inspection and cleaning, but the removal step is significantly easier than with untreated materials.
Standard supply in 1500 × 1500 mm sheets, also 4500 × 1500 mm, in 0.5, 1.0, 1.5, 2.0 and 3.0 mm nominal thickness. For most heating, gas and industrial applications 1.5 or 2.0 mm is standard. Thinner for compact fittings with limited gasket space, thicker where face condition or bolt load requires more material.
At 11% compressibility, BLUESEAL is stiffer than cellulose gaskets. On flanges with adequate bolt load and good face condition, this is an advantage — consistent thickness under load, lower creep. On soft-metal fittings with limited bolt load, a stiffer gasket may not compress evenly. If the fitting is old brass or the bolt load is limited, consider whether FLEXSEAL PRO 350 is the more appropriate choice.
Technical datasheets, approval certificates (DVGW, WRAS, BAM, SVGW, ABS, DNV, EC 1935/2004) and compliance documentation are available per material line for OEM qualification, MRO specifications and regulatory requirements. Contact via the B2B page for documentation requests.
Sizes and packaging
| BSP size | Dimensions (mm) | SKU 25 pcs | SKU 100 pcs |
|---|---|---|---|
| 3/8″ | 14.5 × 9 × 2 mm | B-2014GES32-25 | B-2014GES32-100 |
| 1/2″ | 18.5 × 11 × 2 mm | B-2014GES33-25 | B-2014GES33-100 |
| 3/4″ Normal | 24 × 18 × 2 mm | B-2014GES34-25 | B-2014GES34-100 |
| 3/4″ Special | 24 × 16 × 2 mm | B-2014GES35-25 | B-2014GES35-100 |
| 1″ Normal | 30 × 24 × 2 mm | B-2014GES36-25 | B-2014GES36-100 |
| 1″ Special | 30 × 21 × 2 mm | B-2014GES37-25 | B-2014GES37-100 |
| Box set — 320 pcs — 3/8″ to 1″, 6 sizes | B-2014BOX3 | ||
Custom dimensions and non-standard sizes available on request through B2B contact.
When the medium is demanding, the gasket has to match it. BLUESEAL ULTRA 350 is intended for that service envelope.
Gas. Oxygen. Chemicals. High temperature. Marine. These are the applications where the approval matters, where creep relaxation over months of service is the failure mode, and where a cellulose gasket is simply the wrong material for the job.
BLUESEAL combines approvals and performance characteristics that standard cellulose grades do not typically cover. It carries the approvals that gas and chemical service require, the thermal stability that high-temperature joints demand, and the chemical resistance that oils, fuels and solvents need. When the face condition is the main problem, FLEXSEAL PRO 350 should usually be checked first. When the medium is the challenge, BLUESEAL is usually the next material considered in the specification.