Stainless Steel Weld Neck Flanges
A weld neck flange has a tapered hub that carries load from the flange face into the pipe wall. Its bore matches the pipe. We machine the hub and the matching bore to your drawing from bar or ring stock.
Flow Control & Piping
Stainless Steel Flanges
Profab Machine makes custom stainless steel flanges in 304, 316L, and other stainless grades. We machine blind, slip-on, threaded, and lap joint flanges with the bore, sealing face, and bolt-hole pattern from your drawing or sample. After you send the mating standard, the size, and the quantity, we confirm the design before quoting.
Product Overview
What Are Stainless Steel Flanges?
A stainless steel flange joins two pipes, or a pipe and a piece of equipment, with a bolted joint that can be taken apart for maintenance. Bolt tension squeezes a gasket between the two faces. The squeezed gasket is what creates the seal.
Profab Machine machines stainless steel flanges to your drawing. The bore, the face, and the bolt-hole pattern then match the part the flange bolts to. However, a pressure-rated code flange is a separate product that needs its own engineering review.
Product Range
Types of Stainless Steel Flanges
Each type of stainless steel flange joins the pipe in a different way, so the type decides the welding or threading you need on site.
Stainless Steel Slip-On Flanges
A slip-on flange slides over the pipe. It is then fillet welded on the outside and the inside. This makes it easy to align on site. For your order, we machine the bore to your pipe outside diameter and the bolt-hole pattern to your drawing.
Stainless Steel Blind Flanges
A blind flange is a solid disc that closes the end of a pipe run, a vessel nozzle, or a spare port. We machine the disc thickness, the sealing face, and the bolt-hole pattern to your drawing. We can also add gauge or sample ports on request.
Stainless Steel Socket Weld Flanges
A socket weld flange has a stepped bore where the pipe sits before a single fillet weld. A socket weld flange suits small-bore lines.
Stainless Steel Threaded Flanges
A threaded flange screws onto a pipe with a tapped bore, so the joint needs no weld on the pipe. To tap the thread to your drawing, we need the thread standard, such as NPT or BSP, and the pipe size.
Stainless Steel Lap Joint Flanges
A lap joint flange turns freely on a stub end that is welded to the pipe. That lets you line up the bolt holes without turning the whole pipe spool. We machine the flange and the stub end to your drawing as a matched pair.
Profab Machine machines stainless steel flanges to your drawing but does not rate them for pressure. A pressure class, a code, or a test requirement therefore belongs on your drawing and in your design review.
Material Specification
Choosing the Right Grade
A 304L flange and a 316L flange look the same. However, they behave differently in chloride washdown or salt water.
304 / 304L Stainless
304L is the usual grade for stainless steel flanges in non-chloride service. Examples include water treatment, dry food areas, HVAC, and indoor industrial piping. The L suffix limits carbon to 0.03 percent, which reduces carbide precipitation in the weld heat-affected zone. That matters when the flange will be welded and not annealed afterwards.
316 / 316L Stainless
316L is the grade for stainless steel flanges in chloride-bearing washdown, marine piping, and chemical lines that carry acids or halides. Its 2 to 3 percent molybdenum gives it a pitting resistance number of about 24, which is higher than 304L. We machine 316L flanges from the bar or ring stock you specify.
Other Stainless Grades
We can machine flanges in duplex and other stainless grades on request when the process is more aggressive than 316L can handle.
Passivation and electropolishing are available as finishing services on request when a cleaner surface is needed.
Applications
Diverse Applications of Stainless Steel Flanges
Stainless steel flanges are chosen where the pipe carries something that would corrode carbon steel. They are also chosen where a rust particle in the process is not acceptable.
Flanges for Chemical Processing Lines
Blind flanges close vessel nozzles and spare ports. Machined flanges join acid transfer lines to pumps. 316L resists the acids and chlorides that attack carbon steel.
Flanges for Food and Beverage CIP Lines
Flanges on the pump inlets and outlets of CIP lines for milk, juice, and beer are machined to your face and bolt pattern. 316L withstands repeated caustic and acid washdown.
Flanges for Marine Seawater Cooling Lines
Flanges join seawater cooling lines and ballast piping to pumps and strainers. We machine 316L flanges to your drawing, since salt water corrodes carbon steel.
Flanges for Water Treatment Dosing Lines
Flanges join chemical dosing lines and chlorinated effluent piping to pumps and valves at treatment plants. 304L and 316L resist the chlorine that corrodes carbon steel.
Flanges for Pharmaceutical Process Skids
We machine the bore and face of 316L flanges to your drawing to join pharmaceutical process skids, filters, and tanks to piping. 316L resists batch cleaning chemicals.
Flanges for Pump and Filter Housings
Pump housings, filter housings, and vessel nozzles often need a flange no catalog covers. We machine the flange, bore, and bolt-hole pattern from your drawing or a sample.
Facing Type Selector
Matching Facing to Gasket and Service
The facing decides which gasket a stainless steel flange can take, because the gasket must sit on a face that matches the mating flange. A raised face against a flat face is a mismatch to avoid.
| Facing | What It Is |
|---|---|
| Raised Face (RF) | A raised ring around the bore concentrates the bolt load on the gasket. |
| Flat Face (FF) | This face is used against a flat mating flange, such as one made from cast iron or plastic. |
| Ring Type Joint (RTJ) | A machined groove holds a metal ring gasket. |
| Tongue and Groove (T&G) | One flange has a ridge and the other a groove, which holds the gasket in place. |
| Male and Female (M&F) | One face is raised and the other recessed, which fixes the gasket position. |
| Custom serration | The serration pattern and depth are machined as your drawing states. |
Selection Guide
How to Specify a Stainless Steel Flange
Check these points before you request a quote.
| Factor | What to Confirm | Why It Matters |
|---|---|---|
| Flange type | Blind, slip-on, threaded, lap joint, weld neck, socket weld, or adapter | The type decides how the flange attaches to the pipe. |
| Size | Outside diameter, thickness, and bore | The flange must fit the pipe or equipment it bolts to. |
| Bolt-hole pattern | Number of holes, hole diameter, and bolt circle diameter | A mismatch means the flange will not bolt to its mate. |
| Sealing face | Raised, flat, ring type joint, tongue and groove, or male and female | The face must match the mating flange and the gasket. |
| Material | 304L, 316L, or another stainless grade | The service environment sets the grade. |
| Thread or weld end | Thread standard and size, or bevel and socket depth | The thread or weld end decides how the flange joins the pipe. |
| Drawing or sample | DXF, DWG, STEP, IGES, or PDF, or a worn sample | We machine from the drawing or sample you send. |
| Standard or code | Any standard, pressure class, or test the project requires | Telling us first lets us say what we can supply. |
Why Profab
Your Reliable Stainless Steel Flanges Supplier
01
Bore, Face, and Bolt Holes to Your Drawing
We CNC turn and mill each stainless steel flange ourselves. That way the bore, the sealing face, and the bolt-hole pattern match the part it bolts to.
02
Replacement From a Sample
When you send a worn stainless steel flange or a photo with measurements, we draw the part first. Then we send the drawing for your approval before we machine. Samples take about 20 days.
03
We Say What We Can Supply
If your project requires any class, code, or test, tell us before ordering. Then we can say what we are able to supply.
FAQ
Common Questions
Not seeing your question? Email us at [email protected] and we typically reply same day.
When should I choose a stainless steel weld neck flange instead of a slip-on flange?
A weld neck flange has a tapered hub, so it suits joints that see vibration, pressure cycles, or heat. A slip-on flange is easier to align and cheaper to make, so it suits lines with steady, moderate loads. Your design review sets the choice between them. We machine whichever type your drawing calls for.
Which stainless steel flange face and gasket should I specify?
The face and the gasket must match the mating flange. For example, a raised face takes a flat or spiral wound gasket, while a flat face goes against another flat face. A ring type joint, by contrast, takes a metal ring in a machined groove. We machine the face to suit the mating flange drawing you send.
What stainless steel flange can I use when I cannot weld on site?
A threaded flange screws onto a tapped pipe, so it needs no weld on the pipe. A lap joint flange is also an option, because it turns on a stub end that is welded before the flange is fitted. We quote from the thread standard or the stub end size you send.
Can you machine a stainless steel flange from a sample?
Yes. Send the worn flange or a clear photo with the outside diameter, the thickness, the bore, the bolt-hole count and diameter, and the bolt circle. We draw it first. Then we send the drawing for your approval before we machine. We also accept DXF, DWG, STEP, IGES, and PDF drawings with dimensions.
Do you supply pressure-rated or certified flanges?
We machine stainless steel flanges to your drawing. However, we do not rate flanges for pressure or issue pressure certificates. If your project needs a pressure class, a code, or a material test certificate, tell us before ordering. We will say what we can supply.
How to Order
From Inquiry to Delivery
1
Send Specs
Send the flange type, outside diameter, thickness, bore, bolt-hole pattern, face type, and grade, plus a drawing or sample.
2
Respond Within 24 Hours
Our engineers review your stainless steel flange request or drawing. You receive a specific quote within 24 hours.
3
Production
Standard lead time for stainless steel flanges is 30 days. Custom designs are sampled before the full production run.
4
Delivery
We ship stainless steel flanges by sea, air, or express courier. A tracking number follows once the order ships.
We support small-batch and prototype runs with no hard minimum order quantity. A first prototype run is typically around 100 pieces.
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If you already have drawings, email [email protected] directly and we will quote from them.
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