Refractory Anchors

Refractory Anchors Specializes in the Manufacture of High Temperature Alloy and Stainless Fasteners Used to Anchor Refractories in Furnaces and Process Equipment. refractory anchor hardware is wire formed,die stamped, roll threaded and welded into a variety of anchoring products for castable monolithic, abrasion resistant and ceramic fiber refractory linings.

Benefits of Refractory Anchors

Industrial furnaces, kilns, reactors, ovens, and vessels utilize extreme temperatures to cause chemical reactions or physical changes in workpieces. In most cases, these extraordinary conditions would immediately destroy the application’s shell. For this reason, materials that are resistant to heat, pressure, and chemical degradation are used as a protective barrier. Commonly called refractories, refractory materials, or refractory linings, they provide a range of benefits.

Prolong application lifespan  Enhance application performance Protect against corrosion

Provide thermal insulation Withstand physical stresses and prevent erosion of vessel walls due Serve as a thermal barrier between a hot medium and the wall of a containing vessel

To optimize refractory lining performance, anchoring systems are used to secure refractory castables, board, ram plastics, fiber insulation, and ceramic fiber modules to the furnace or kiln shells. These devices are manufactured from heat-resistant stainless steel and nickel alloys and serve several purposes.

• Hold the refractory to the wall to keep it from falling in
• Prevent wall buckling due to the internal thermal stresses created by high temperatures
• Help support the load of the refractory weight

Refractory Anchor Material Types

When you need high-quality refractory anchors, Delta Stud Weld is here to help. As a leading refractory anchor supplier, we can hastily deliver these fastening devices in various sizes and configurations.

Refractory hardware must be manufactured from high-quality materials because, being closest to the hot face, they experience the highest temperatures. Delta Stud Weld manufactures all high-temperature refractory hardware using materials sourced from trustworthy domestic mills. Examples include stainless steel refractory anchors or nickel alloy refractory accessories. Here are the materials we typically use:  

304 stainless steel  310 stainless steel

330 stainless steel  601 Inconel

Off-the-shelf products aren’t always the best option. Delta Stud Weld specializes in the quick turnaround of custom refractory anchoring solutions. Whether it’s a vetted drawing or an idea that has not yet been fully realized, our knowledgeable engineering team can take your plan from design to finished product swiftly and efficiently. 

Inspectors use precision gauges to verify conformance with applicable industry standards or customer requirements. All raw material is checked for accuracy, and Material Test Reports can be supplied with shipments upon request. Orders are audited before load out.

INFORMATION

« PLASTIC » CAPS ON TIPS OF ANCHORS

Steel alloys (AISI 310, 304 …) used for manufacturing anchors have a thermal expansion which is much greater than refractory castables (average: 1.5 mm per meter per 100°C).

Metallic anchors are within the castable structure, they expand more than the castable, and this creates stress in the castable. The stress can generate cracks, which in turn can produce spalling. The longer the anchor, the greater will be the difference in thermal expansion and the higher will be the stress inside the castable layer. The way to manage the thermal expansion difference is to put on the tip of the anchors a so called “plastic” cap, which will melt at about 150°C, and will then give a small space into which the higher thermal expansion steel alloy can move without creating stress within the castable.  Most of the anchors suppliers use “plastic” caps, the plastic is usually PVC, the C of PVC is Chlorine a small quantity indeed, never the less chlorine, which is NOT good for castable or steel alloy.  A much better option is to use POLYETHYLENE CAPS which are chlorine free ANCHORS offers the two options. PVC CAPS are softer which enables a faster and cheaper installation on the anchors but they contain chlorine POLYETHYLENE CAPS cost a bit more but are chlorine free.  If you don’t mention your preference, it will be PVC.  Please write Polyethylene caps (PE caps) if you need them.

 

DEFINITION/SPECIFICATION OF REFRACTORY ANCHORS (proposal)

A detailed drawing has to be attached to the specification ; the alloy has to be mentioned. Refractory anchors will be manufactured from a cold drawn wire, DIN 671 , EN 10278,h9.

That means the tolerance on diameter 6 : +0 ‐ 0.030 mm, On diameter 8 : +0 ‐ 0.036 mm

Anchors are submitted to normal manufacturing tolerances.In general, the dimensional tolerance average is :

1.+/ ‐ 5 ° on angle

2.+/ ‐ 2 ° for height <200 mm

3.+/ ‐ 5 mm for height >200 mm

The wire will have a smooth,shiny surface. Any other type of wire won’t be accepted( for instance wire rod). Tensile strength of the wire will be between 600 and 750 N/square mm. Anchors will be formed according to a soft bending technique, by robotic machines,in order to minimize the stress, the bending marks and to avoid micro cracks through which corrosion penetrates faster. Using mechanical presses for the anchors forming is not accepted. Possible bending marks will not be deeper than 0.15 mm for diameter 6 mm,0.20 for diameter 8 mm and 0.25 for diameter 10mm. If caps are used on top of anchors, they will be in polyethylene. Most manufacturers use PVC caps( softer, faster to install and cheaper). C of PVC is chlorine, which is agressive on the refractory castable. The anchor supplier will give to its customer the mill certificate 3.1.B issued by the steel plant who has manufactured the wire used for manufacturing the refractory anchor.

SOLUTION ANNEALING AFTER FORMING OF REFRACTORY ANCHORS

Our anchors manufactured in round sections( wire in coils) are made from wires which are solution annealed in the stainless steel plants. After annealing, the wires are cold drawn. Sometimes ( rarely), some customers ask for anchors solution annealed after forming.

The target of that annealing is to relieve the stress generated by the forming of the anchor. Indeed, if the anchors manufacturer is not using the right high quality wire and is forming the anchor with mechanical tools or presses( both are very usual in China and India,quite common in the western world), micro cracks,weak areas ,unhomogeneity of physical properties of anchors will be encountered. We make round anchors with robots, using hydraulic processes,operating at low speed, doing what we call the « soft bending ».

Because of :

-The type of wire we are using

-The process of forming

We generate very low stress when we form anchors and the solution annealing after forming is not required for our anchors made from wire.

Nevertheless, If your specification does require the solution annealing, you have 2 options :

Anchors are heated in a furnace with a traditional oxydising atmosphere.

The anchors, clean and shiny before the annealing, will become black, looking dirty( oxydes layer on the steel alloy)

 

BRIGHT SOLUTION ANNEALING

SOLUTION ANNEALING UNDER VACUUM OR UNDER SPECIAL ATMOSPHERE

Some customers don’t like the black dirty aspect of the anchors after traditional oxydising annealing.

They ask for « bright annealing »

This is done either :

-in a furnace operating under vacuum, having no air, no oxygen,there is no oxydation.

-in a furnace operating under a special atmosphere which is a combination of :

-nitrogen,neutral/protecting gaz

-Hydrogen,reducing gaz

Once again, no air, no oxygen, then no oxydation and the reducing effect of hydrogen, dissociating oxydes.

NB- This annealing is more expensive than the standard solution annealing.