Who manufactures flanges in India to ASME B16.5?
Kalp Alloys is a flange manufacturer based in Ahmedabad, Gujarat, India. It produces weld neck, slip on, blind, socket weld, threaded, lap joint, orifice and RTJ flanges to ASME B16.5, ASME B16.47 Series A and B, EN 1092-1, DIN and BS 4504, in Class 150 to Class 2500 and NPS 1/2 inch to 48 inch.
Key Takeaways
- Kalp Alloys manufactures flanges at its own facility in Rakhial, Ahmedabad — it is a producer, not a stockist reselling another mill’s material.
- Standards covered: ASME B16.5, ASME B16.47 Series A and B, ASME B16.36 (orifice), EN 1092-1, DIN 2631–2638, BS 4504, MSS SP-44 and API 605.
- Pressure classes run Class 150, 300, 400, 600, 900, 1500 and 2500, plus PN6 to PN64 on the European range.
- Size range is NPS 1/2 inch (15 NB) through 24 inch (600 NB) as standard, extending to 48 inch (1200 NB) on order.
- Every flange ships with an EN 10204 3.1 or 3.2 mill test certificate carrying the heat number, so the buyer holds traceability rather than a trader’s declaration.
- Third-party inspection by SGS, BV, TUV or Lloyds and NACE MR0175 / MR0103 compliance for sour service are available on request.
What a manufacturer supplies that a marketplace cannot
Most search results for flange supply in India resolve to trading platforms and stockist directories. They aggregate. A buyer who orders through that layer receives material produced by an unnamed mill, and the certificate that arrives is a copy passed along the chain rather than a document issued by the party who melted and forged the part.
Kalp Alloys forges, machines and tests at a single facility at 5, Jay Vijay Industrial Estate, Rakhial, Ahmedabad. The heat number stamped on the flange face traces back to our own melt record, the dimensional report is produced by our own inspection bay, and the EN 10204 3.1 certificate is issued in the name of Kalp Alloys. When a project auditor asks who made the part, there is one answer and one document, not a chain of intermediaries.
That difference matters most where it costs most: on sour-service lines governed by NACE MR0175, on refinery shutdowns where a rejected certificate stops a weld, and on approved-vendor submissions where the mill name on the MTC decides whether a package clears at all.
| Factor | Kalp Alloys (manufacturer) | Marketplace / stockist |
|---|---|---|
| Mill test certificate | Issued in Kalp Alloys’ own name, EN 10204 3.1 or 3.2 | Passed through from an unnamed third-party mill |
| Heat traceability | Heat number ties to our own melt and forging record | Traceable only as far as the stockist’s purchase |
| Non-standard sizes | Made to drawing on our own forging line | Limited to whatever the stock holder carries |
| Third-party inspection | Witnessed at our Ahmedabad plant | Witnessed at a warehouse, after production |
| Technical query | Answered by the team that made the part | Relayed to a supplier and back |
| Lead time on stock sizes | 3 to 7 days ex works | Dependent on stockist availability |
Flange types manufactured
The full ASME B16.5 and B16.47 type range is produced in-house, in raised face (RF), flat face (FF) and ring-type-joint (RTJ) facings. Facing finish is supplied to the serration standard the specification calls for — typically 125 to 250 AARH for a raised face gasket seat.
- Weld neck (WNRF) — long tapered hub butt-welded to the pipe. The default choice for high pressure, cyclic loading and elevated temperature because the hub transfers stress into the pipe wall gradually.
- Slip on (SORF) — slides over the pipe, fillet welded inside and out. Lower cost and forgiving on alignment; not used where fatigue or thermal cycling governs.
- Blind (BLRF) — solid disc closing a line, vessel nozzle or valve opening. Carries the highest bolt-induced stress of any type in the set.
- Socket weld (SWRF) — small-bore lines, typically 2 inch and below, with the pipe seated in a machined recess.
- Threaded / screwed — used where welding is prohibited, such as certain utility and instrument air services.
- Lap joint — runs with a stub end so the flange can rotate for bolt-hole alignment; common on lined and exotic-alloy piping where only the stub end need be in the costly grade.
- Orifice — paired flanges with jack screws and pressure tappings for a flow-measuring element, to ASME B16.36.
- Long weld neck, spectacle blind, spacer and ring — produced to drawing.
Grades and material standards
Grade selection is driven by the service — temperature, pressure, chloride content, hydrogen sulphide partial pressure and the code the plant is designed to. The table below maps the material families produced at Ahmedabad to the ASTM specification and the service each is normally specified for.
| Material family | ASTM / ASME specification | Typical grades | Normally specified for |
|---|---|---|---|
| Carbon steel | ASTM A105 / A350 LF2 | A105N, LF2 Cl.1 | General hydrocarbon and utility service; LF2 for low-temperature duty |
| Stainless steel | ASTM A182 | F304, F304L, F316, F316L, F321, F347 | Corrosive process service and hygienic lines |
| Alloy steel | ASTM A182 | F5, F9, F11, F22, F91 | Elevated-temperature steam, hydrogen and refinery heater service |
| Duplex & super duplex | ASTM A182 | F51 (2205), F53 (2507), F55 (Zeron 100) | Chloride-bearing and seawater service where pitting governs |
| Nickel alloys | ASTM B564 | Inconel 625, Incoloy 800/825, Monel 400, Hastelloy C276 | Aggressive acids, high temperature and severe corrosion |
| Titanium | ASTM B381 | Grade 2, Grade 5 | Seawater, desalination and chemical service at low weight |
| Copper alloys | ASTM B151 / B171 | Cu-Ni 90/10, Cu-Ni 70/30 | Marine cooling water and heat exchanger duty |
Documentation supplied with every consignment
A flange that cannot be documented cannot be installed on a code-governed line. The standard document pack is issued without being asked for, and additional certification is added where the specification calls for it.
- Mill Test Certificate to EN 10204 3.1, or 3.2 where an independent inspector must countersign.
- Chemical composition and mechanical property results against the ordered ASTM grade — see our chemical composition and mechanical properties reference tables.
- Dimensional inspection report against the ordered standard and class.
- Heat number traceability linking the finished part to its melt.
- NDT records where specified: radiography, ultrasonic, magnetic particle or dye penetrant.
- Hydrostatic test report where the item is pressure tested.
- PMI (positive material identification) report on request, confirming the alloy at the finished part rather than at the billet.
- NACE MR0175 / MR0103 compliance statement for sour service, and hardness survey results supporting it.
- Third-party inspection release note from SGS, BV, TUV or Lloyds where the project mandates it.
The full document set is explained on the EN 10204 mill test certificate page, including how to read each block of the certificate and what to check before accepting material.
Ordering, lead time and dispatch
Send grade, size or NPS range, pressure class, facing, quantity and the required certification level. A quotation is typically returned within 24 hours. Drawings for non-standard items can be sent by email or on WhatsApp at +91 81608 73937 and are reviewed by the technical team rather than a sales desk.
Stock sizes dispatch in three to seven days. Made-to-drawing items carry a firm lead time quoted at order confirmation. There is no minimum order value on stock sizes and trial quantities are accepted, because a buyer specifying a new source reasonably wants to inspect material and documentation before committing a project quantity.
Domestic dispatch runs by road from Rakhial, Ahmedabad. Export consignments move through Mundra, Kandla or Nhava Sheva with seaworthy packing, fumigated wooden cases where required and the full export document set — described in detail on the export process page.
Frequently Asked Questions
Kalp Alloys is a manufacturer. Forging, machining and inspection are carried out at our own facility at 5, Jay Vijay Industrial Estate, Rakhial, Ahmedabad, and the EN 10204 mill test certificate is issued in the name of Kalp Alloys rather than passed through from another mill.
ASME B16.5, ASME B16.47 Series A and B, ASME B16.36 for orifice flanges, EN 1092-1, DIN 2631 to 2638, BS 4504, MSS SP-44 and API 605. Pressure classes run Class 150 to Class 2500 and PN6 to PN64.
NPS 1/2 inch to 24 inch is standard under ASME B16.5. Larger diameters from 26 inch to 48 inch are produced under ASME B16.47 Series A and B on order.
Yes. Flanges can be supplied compliant with NACE MR0175 / ISO 15156 and NACE MR0103, with hardness survey results supporting the compliance statement in the document pack.
Yes. Non-standard bores, thicknesses, drilling patterns and facing finishes are produced to customer drawing. Send the drawing by email or WhatsApp and the technical team responds with grade and forging options.
There is no minimum order on stock sizes, and trial quantities are accepted so a buyer can verify material, documentation and packing before placing a project order.
Stock sizes dispatch in three to seven days from Ahmedabad. Made-to-drawing items are quoted with a firm lead time at the point of order confirmation.
Yes. Kalp Alloys exports through Mundra, Kandla and Nhava Sheva to the UAE, Saudi Arabia, Qatar, Oman, Kuwait, the United States, the United Kingdom, Nigeria, Singapore, Malaysia and South Africa, among other markets.