Stainless Steel Pipe Manufacturer in India: Grades and Quality

Decades ago, Stainless Steel Pipe Manufacture in India was easy, but that is no longer the case. Finding the right manufacturers has in fact become more difficult over time because the number of manufacturers has increased. Mumbai, Ahmedabad, Rajkot, and the industrial regions of Maharashtra and Gujarat are now home to hundreds of manufacturers. Each claims to sell certified materials at low prices. The challenge lies in distinguishing manufacturers that design and test their own pipes from traders who package someone else's pipes and hope that no one checks. 

Stainless steel pipes do not break conveniently. The consequences of a broken pipe extend beyond a loss of the value of the steel. Pipe failure in a chemical line, a pitted pipe in a food processing line, or a corroded pipe in a utility loop in a pharmaceutical plant, all pose serious safety concerns. Procurement managers learn first hand to shy away from the lowest quote after having experienced an incident. Learning how a manufacturing facility operates and how the material should be documented is the best way to avoid problems that might occur during the supply of materials.

The Two Processes that Make Stainless Steel Pipe and Why it Matters 

There are two main processes that can create a finished pipe. The first, seamless process, shapes a solid billet of stainless steel by moving it along a mandrel. Seamless pipes can accommodate a wide range of applications because there is no weak spot caused by a weld. Thus seamless stainless steel pipes are the go-to pipes for high-pressure hydraulic pipes or boilers. 

On the other hand, welded pipes undergo a different process. Plate or tube shaped stainless steel has multiple segments that are TIG or HFI welded along the length. Welded pipes on the consumer market are actually excellent pipe products due to advanced technological processes that include automated welding, solution annealing, and internal testing that ensure high levels of performance for any application. The pipe truly shines in performance relative to its cost for seamless pipes. It does have some shortfalls for certain applications for super-high pressures and some sour service pipes where the pipe seam is not allowed to penetrate. 

Heat treatment is the most important step in determining final quality. Solution annealing dissolves chromium carbides that happen during working and welding and creates the uniform austenitic structure to give stainless its corrosion resistance. If a manufacturer skips this step or runs this step too quickly, they can deliver a pipe that appears perfect, but is actually very reactive and corrodes quickly. Both of these steps have to be done; their absence is one of the biggest reasons cheap pipe is disappointing for actual use.

What Differentiates a Real Manufacturer From an Importer 

The Indian market appreciates customers who ask specific questions. Real Stainless Steel Pipe Suppliers will be happy to answer any question, since these answers define their business, rather than being bothersome.

Testing Infrastructure You Can Physically Verify 

What testing do they perform in house? A legitimate manufacturing plant does their own spectrochemical analysis, hardness and tensile tests, flattening and flaring tests and ASTM A262 intergranular corrosion testing and some form of NDT (Eddy current, ultrasonic or radiographic testing) based on the specification and also does hydrotesting. Every facility that subcontracts everything is an assembler, not a manufacturer. Take them up on a tour of the laboratory and you will learn everything you need to know in 15 minutes that would take you a week by email.

Certificates Dating Back to a Heat Number 

Every consignment needs to have an EN 10204 3.1 certificate associating a heat number with a documented chemical composition and mechanical property tests, which needs to be stamped or engraved on the pipe. Confidence is shown by suppliers commissioning third party inspections from Lloyds, TUV, SGS or BV and allowing Positive Material Identification at the dispatch. There is no clearer indication of what is lacking than vague documents or reluctance to allow inspection.

Range of Grades and Real Stock Depth 

Be wary of producers who do not possess a good understanding of the differences between the 304, 304L, 316, 316L, 310, 321, 317L, duplex 2205, and super duplex 2507. The supplier who can justify the choice of one over the other for your application is worth contacting. Confirm what stock dimension is currently available for your requirement. Real stockists respond immediately. Intermediaries have to call back later.

Grades and Understanding Specifications for Your Application 

There are more failures that occur in the field as a result of grade being selected incorrectly than due to manufacturing defects. The 304 series is appropriate for use in architectural applications, building services, contact with food, and slight exposure to chemicals. The addition of molybdenum produces 316, which is suitable for use in environments that involve coastal air exposure, marine services and process streams with salts. The low carbon versions 304L and 316L are better suited to situations where sensitization is of concern and the modest price difference of these is usually justified. 

The specialist grades start on the 300 side. Grade 321 is reinforced with titanium for elevated temperatures. Grade 310 is for repeated use in even more elevated temperature furnaces or kilns. Duplex grades contain both austenitic and ferritic structures, which doubles the strength of the 304 grade, while at the same time offering superior resistance to stress corrosion cracking. This results in thinner walls and a lower total weight for the component. 

Equally important is the standard. The ASTM A312 standard provides for the use of seamless or welded austenitic pipe for high temperature service and resistance to general corrosion. A358 addresses electric fusion welded pipe, A790 covers duplex stainless steel, and A269, or A213, cover tubing. In conjunction with the grade, specifying the proper standard also provides clarity as to what is expected and what is to be provided.

Pricing, Lead Times, and the Invisible Costs 

Stainless costs are also driven by nickel and chromium as are currency rates. Given this volatility and the fact that all three move every week, a quote with a thirty-day validity is either optimistic or has been hedged with a premium.

What Shapes the Quote 

Seamless stainless is always more expensive than welded, as is the case for pipe with identical dimensions. More difficult to fabricate round sections with thin walls carry a higher price and increased costs per kilogram. Tests and inspections, more stringent tolerances and commercially useful lengths all have a cost impact.

Realistic Delivery Expectations 

Lead times on stock items are within days. Custom orders generally take six to twelve weeks, depending on grade availability and the current order backlog. Specialty imports may take even longer. Manufacturers who claim to offer custom seamless production in just two weeks at best have stock, and at worst are committing to deliveries they simply cannot fulfill. On the other hand, realistic lead times enable you to plan. Optimistic lead times will certainly cost you at the job site.

Creating a Strong Supply Relationship

The strongest supplier relationships are built prior to emergencies. Get out in the field and check on material segregation and procedures for separation of carbon steel and stainless steel tooling and shipping of finished pipe that is properly capped. You should also check on the quality of packaging and also monitor the process for documentation. Prior to ordering the more important materials, you should place a smaller order and monitor the entire process for documentation and communication.

This groundwork places you in an advantageous position prior to your competitors in quote comparisons. When nickel spikes or mills run late, clients that have established relationships get an early heads up on the impact to the schedule, while other less important clients get the information after the fact. The value of having suppliers that refuse to take on orders that they are not capable of fulfilling is worth much more than having a supplier unwilling to place any restrictions on orders and has a consistently poor delivery record. For various engineering and procurement teams, Eramets Steel Alloys is an excellent option to start.