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Today I am going to share some knowledge of ASTM A554 stainless steel welded slotted tubes for you.

There are two ways to produce a stainless steel slotted tube:

  • Produced by molding directly
  • Bending by machine.

Let us talk about the produced by mold first:


 

STAINLESS STEEL RAW MATERIAL

Our main material is in grade 304/316L/2205,  For each new specification, our engineers will use CAD software to accurately calculate the perimeter of the slotted tube (Difference thickness with different coil width). Then our purchaser will arrange the raw material accordingly, it will back to our factory after 5-7 days.

stainless steel coil for glass handrail systems

TUBE FORMING PROCESS

If it is a new specification, we need to open the mold, the cost of the new mold is between $2,500 and $12,500. Mold time is 12 days after the sample confirmed.

During the tube forming process, it takes about  20 sets of molds, the first 13 sets of molds are for groove forming, there are 2 sets of molds in the middle to make the tube shape in the round, the last 2 sets of molds are for the straightening. Why do our machines need so many molds? Before the mass production, we need the 6 steps as follows:

1). After installing the mold, our engineer will pull the central axis to ensure the straightness within 1mm/meter.

2). Put the pipe coil into the machine.

3). Extrusion by mold.

4). Welding. we will join the Nitrogen to protect the welding place.

5). Perform multiple debugs on the machine.

6). Welding inspection.

7). 100% inspection.

quality control for stainless steel welded tube

quality control for stainless steel welded tube

We hereby certify that the stainless steel described herein has been manufactured by the standards and specifications specified by you and that it satisfied the requirements.

  • Outer diameter tolerance: +/-0.2mm.
  • Thickness tolerance: +/-10%.
  • Slotted tolerance: +/-0.3mm.
  • Cut length tolerances all at +/- 5mm.
  • Both ends de-burred washed and dried.
  • Both ends must be cut completely ‘square’.
  • Our customer will highly recommend that ‘go’ / ‘no go’ gauges be made for both outer diameter and inner diameter as both are critical due to both external and internal fittings being assembled.

stainless steel top railing

Stainless steel top railing

Our available stainless steel groove tube size as follows:

Size list for stainless steel u tube

Size list for stainless steel slot tube

Size list for stainless steel slot tube

size list for stainless railing tube

POLISHING

After the tube forming process, the tube will be sent into the polishing workshop immediately. The staff will install the polishing material according to the order finish. Normally, the satin finish and simple mirror finish will need to polishing 3 times, if you requested an 8K super mirror finish, that needs to polishing over 10 times.

Both ‘mirror polished’ and ‘Dull Polished’ must be produced to ‘color/finish match’ the handrail fittings (which are die-cast zinc and :

  • Chrome plated (‘mirror’) finish: 400#, 600#, 8K, 10K Super mirror.
8K super mirror finish stianless steel tube

ASTM A554 super mirror finish stainless steel tube

  • Brushed and Nickel plated & lacquered dull polished finish (round direction): 180#, 240#, 320#, 400# brushed.

ASTM A554 stainless steel brushed tube

100% INSPECTION

Our staff will 100% inspect for the stainless steel railing tube.

  • At the beginning of the raw material, our QC will use our stainless steel chemical analysis machine to check all the chemical composition for each pipe coil. (304 the carbon should below 0.08%, a nickel above 8%, and the CR above 18%;  316L Carbon max 0.035%, Nickel be 10-15% and CR 16-18%.

stainless steel coil chemical composition analysis

304 stainless steel chemical composition

  • During the tube forming process, our staff will adjust the mold to ensure the diameter within tolerance, adjust the machine according to customer‘s railing fittings, and at the end of the tube machine, in the meanwhile, they will also check the straightness of tube piece by piece, then they will pick the tube out piece by piece to avoid the snatch on the tube surface.

stainless steel tube forming process

  • At the polishing stage, our employee will take the tube out one by one, then put it into the wooden frame separately. Besides, each layer is separated by a cloth. All work is done to avoid the tube surface being touched.

stainless steel balustrade tube

  • After 1 time polishing, our QC will use a pen to circle the sand hold on the surface piece by piece, grind the surface with a water mill, then re-polishing it.

water mill for stainless steel welded tube

  • After completed polishing, at the same time, we will double-check the stainless steel handrail baluster with the customer’s fitting, both sides of the groove tube will be inspected.

Quality control for stainless steel groove tube

PACKAGE

We have a various export package for stainless steel U tube. Here are some common packagings:

PLASTIC BAG:

  • White transparent plastic bag, the thickness of the general plastic bag refers to the bag thickness before opening. Commonly used 0.05mm thick plastic bag, 1C=0.01mm.
  • Normally, If our customer needs a thick plastic bag, we will ask for a sample if he has one.
  • If the quantity is too small, it cannot be customized. In this case, we will negotiate with our purchaser department if we can process the plastic bag according to customer demand.
  • Surely, the price of the customized plastic bag will be higher than the original one. And we will add the price to the quotation.
  • There will also be a situation where the customer’s order has different outer diameter specifications, some small tubes are narrow bags, need to communicate with our purchaser department, and the width of each size bag, whether the quantity reaches the MOQ of the purchasing bag, In order to respond to customers can be packaged as required.

stainless steel tube package

50KG WOVEN BAGS:

  1. Woven bags are usually used for bundling.
  2. Inside is a single tube packed in a white transparent plastic bag, which is bundled into several bundles.
  3. The gross weight is controlled at 50kg / bundle, which is convenient for some customers who do not have forklifts and can arrange to unload by hand.
  4. The round tube is usually wrapped into a circle, and the rectangular tube is packed in a flat shape.
  5. The shipping marks will be stuck to both ends.
  6. This kind of packaging has been commonly used in North Africa, Russia, South America (including Brazil and Colombia anti-dumping), Southeast Asia (Thailand anti-dumping), India (customers ignore), Turkey (anti-dumping)
  7. This kind of packaging requires manual installation when loading containers. A 40GP / HQ with 6 meters can hold 25-27 tons. The 5.8-meter tube can hold 25 tons.

500KG/BUNDLE SEA-WORTHY BAG:

  1. The sea-worthy bag is 500KG / bundle normally.
  2. All the stainless tube will be loaded by the forklift.
  3. In this package, 1x40GP / HQ container can be loaded approximate 25-27 tons with 6 meters long tube. The 5.8-meter long tube can be loaded into 1x20GP with 25 tons. In general, 6-meter-long stainless steel welded tube is the most popular one.
  4. During the loading, our staff will leave a belt for each package,it would help our customers easy to unloaded.

SHRINK WRAPPED FILM

  1. For the brushed finish, our tube will be packed into the shrink-wrapped film separately. But we will join the 2-layers package to protect the stainless steel 8K mirror tube. The plastic bag inside with a shrink-wrapped film outside could reduce the scratches on the surface of the tube. Because the heat shrink film is a bit hard, and the surface of the tube may be scratched during packaging.
  2. In general, 304 stainless steel in green shrink foil, and 316L in red color shrink foil.

316L-Red-Shrink-film-wrapped

CARDBOARD PAPER TUBE:

  1. Part of our customers will demand the U tube packed into the shrink-wrapped film with a cardboard paper tube, both ends of the paper tube will be covered by a plastic end cap(color is blue, another color is available if the quantity is good).
  2. In general, the color of the cardboard paper tube is neutral, but the color is customizable.

cardboard paper tube for stainless steel grooved tube