We are HuaboPipe, a Chinese manufacturer of forged flanges in duplex 2205 and super duplex 2507. We make weld neck, long weld neck, slip-on, blind and lap joint flanges to EN 1092-1 or approved drawings. EN 10204 3.1 mill test reports are available on request, with material traceability.
Duplex and super duplex flanges we make
We supply duplex 2205 and super duplex 2507 forged flanges. Our scope covers ASTM A182 F51/F60 and F53, with the final designation agreed against your purchase specification.
| Common name | ASTM A182 grade | UNS | W.Nr |
|---|---|---|---|
| Duplex 2205 | F51 | S31803 | 1.4462 |
| Duplex 2205 | F60 | S32205 | 1.4462 |
| Super duplex 2507 | F53 | S32750 | 1.4410 |
"2205" alone does not settle every designation question, so we do not treat F51 and F60 as interchangeable; please state the full ASTM grade and UNS designation.
HuaboPipe was founded in 2004, with the company in Wenzhou. The factory is in Lishui, Zhejiang. We export to 60+ countries.
Flange types available in duplex 2205 and 2507
We make weld neck, long weld neck, slip-on, large-diameter slip-on, blind, non-standard blind and lap joint flanges with stub ends. RF is our standard facing; FF and RTJ are supplied to drawing.
The table describes our manufacturing scope; not every type, size and facing combination appears in every standard.
| Flange type | Standard or manufacturing basis | Facing |
|---|---|---|
| Weld neck | EN 1092-1 or approved drawing, as specified | RF; FF or RTJ to drawing |
| Long weld neck | Specified standard or approved drawing | RF; FF or RTJ to drawing |
| Slip-on | EN 1092-1 or approved drawing, as specified | RF; FF or RTJ to drawing |
| Large-diameter slip-on | Specified standard or approved drawing | RF; FF or RTJ to drawing |
| Blind | EN 1092-1 or approved drawing, as specified | RF; FF or RTJ to drawing |
| Non-standard blind | Approved drawing | RF; FF or RTJ to drawing |
| Lap joint with stub ends | Specified standard and approved assembly details | Per specified standard or drawing |
For weld neck flanges we need the connecting pipe details and bore; for lap joint assemblies we review the backing flange and stub end together.
Standards, pressure classes and size range for our flanges
Flanges are made to EN 1092-1. Larger sizes are made to drawing, up to DN3000.
Pressure-temperature limits follow the ratings for the material group in the standard you specify, such as EN 1092-1.
A pressure class is not a universal pressure allowance; drawing-based flanges need your engineer's approval of the design basis.
2205 vs 2507: which grade for your line?
In our experience, 2205 is the cost-effective default for most chemical and brackish water lines. Buyers choose 2507 for harsher chloride service, such as seawater, offshore and desalination. If you are not sure, tell us the medium, temperature and pressure. Your engineer or materials specialist approves the final grade.
When comparing offers, compare the approved grade, manufacturing route, inspection scope and documents, not just the alloy name.
Testing, inspection and documents
PMI inspection available. Dimensions are checked. PT, UT, RT and hydrotest are done per order. Third-party inspection by SGS, BV or TÜV is accepted. EN 10204 3.1 mill test reports are available on request.
Process: forged → solution annealed → machined and drilled → pickled and passivated.
| Testing activity | Availability or basis | Extent and acceptance criteria |
|---|---|---|
| Dimensional check | Included in our inspection scope | Approved standard or drawing |
| PT | Per order | Per the standard or specification on your order |
| UT | Per order | Per the standard or specification on your order |
| RT | Per order | Per the standard or specification on your order |
| Hydrotest | Per order | Per the standard or specification on your order |
| PMI | PMI inspection available. | Per order |
| Document or inspection arrangement | Our provision |
|---|---|
| EN 10204 3.1 MTR | Available on request, with full material traceability |
| EN 10204 3.2 | Available on request |
| SGS / BV / TUV inspection | We support the agreed scope |
| Additional project document requirements | Agreed at the inquiry stage |
EN 10204 3.2 material certificates are also available on request. If you need 3.2, or have hold and witness points, state this in your inquiry so it is agreed before production.
Approvals behind our duplex flanges
Certificates: PED, DNV (since 2018), BV. See the certificates page. We also hold ISO 9001, ISO 14001 and ISO 45001 certifications.
Certificate copies (PED, DNV, BV, ISO 9001/14001/45001) are available on request.
What to send for a quote
Send your flange schedule together with any specification or drawings. Mark any open items and we will flag them in our review. Please include:
- Common alloy name, ASTM A182 grade and UNS designation
- Flange type, nominal size and quantity
- Standard and edition, or approved drawing revision
- Pressure class or designation, and facing
- Connecting pipe or stub end details where applicable
- Testing methods, acceptance criteria and inspection points
- Required document package and any third-party inspection
- Delivery destination and requested schedule
- Medium, temperature and pressure, if the grade is not yet decided
For combined flange and butt-weld fitting orders, list each item separately.
FAQ
Are your duplex flanges forged?
Yes, they are forged flanges.
Can I specify F51 and F60 interchangeably?
We do not assume they are interchangeable. Please state the full ASTM grade and UNS designation, and we will ask for engineering confirmation if the description is unclear.
Can you make DN3000 flanges?
Yes. Large sizes are made to drawing, up to DN3000.
Do you issue EN 10204 3.2 certificates?
Yes. EN 10204 3.1 mill test reports are available on request, with full traceability. EN 10204 3.2 is also available on request.
Should I choose 2507 for seawater service?
2507 is the usual choice for harsher chloride service such as seawater. Send us the medium, temperature and pressure so your engineer can confirm the grade.
Can you supply flanges and butt-weld fittings together?
Yes. We can combine duplex flanges and duplex butt-weld fittings in one order, with separate requirements for each item.
Where do I send my inquiry?
Email lucas@hbpipe.com or WhatsApp +86 152 1057 8298.
Send your duplex flange list or drawing to lucas@hbpipe.com or WhatsApp +86 152 1057 8298 for a quote.
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