A refinery turnaround crew in Saudi Arabia had four days to reline a crude heater. They had the modules on site, the scaffold was up, and the anchor studs were already welded to the shell from the original installation. The crew supervisor was confident - until the first row of modules went up and the compression bands were cut, and the modules expanded unevenly, leaving a 15mm gap between two adjacent blocks that should have sealed tight.
The crew lost half a shift figuring out that the stud pattern on the shell did not match the module backing plate layout from the new supplier. The original installation used 300mm-center anchors. The new modules were built on a 310mm pattern. The fix required cutting and re-welding forty anchor studs inside a confined furnace shell at 45°C ambient temperature. The job finished, but it cost the refinery an extra day of downtime at a rate they preferred not to discuss.
Ceramic fiber module installation is not complicated compared to brick laying. But it is unforgiving: a small error in anchor placement, compression release sequence, or joint sealing becomes a large repair bill after the furnace is back online. This guide walks through the process step by step, with attention to the details that cause the most field problems.
Before You Start: The Three Things to Verify on Day Zero
1. Shell preparation
The steel furnace shell must be clean, dry, and free of rust scale, oil, or old refractory residue. Anchor studs need a clean welding surface - any contamination in the weld zone weakens the stud attachment. If the shell has been grit-blasted, blow it down with compressed air to remove dust before starting anchor layout.
2. Anchor stud layout vs module dimensions
This is where the Saudi crew got caught. Module backing plates have a specific anchor hole pattern - typically matching the stud spacing on the shell. Before any module goes up, lay out the first row of studs and physically check one module against the pattern. The module should slide onto the studs without forcing. If it does not, fix the stud layout now - not after ten modules are already bolted down.
Standard stud spacing for 300×300mm modules is 250-280mm center-to-center, with the studs typically M8 or M10 and welded perpendicular to the shell. The exact spacing depends on the module supplier's backing plate design - confirm it from their installation drawing, not from the last project's drawing.
3. Module orientation plan
Ceramic fiber modules have a fold direction. The folds should run perpendicular to the direction of the furnace gas flow. If gas flows vertically up the furnace wall, the folds should run horizontally so that the seam between module layers does not face directly into the gas stream. Sketch the row layout before starting so every module goes up in the correct orientation.
Step 1: Weld Anchor Studs to the Shell
Use stud welding equipment with the correct ferrule size for your stud diameter. Each stud should be welded with a single-shot capacitor discharge or drawn-arc process depending on the stud type and shell thickness. After welding, test every stud with a hammer test - strike the stud from the side with a 1 kg hammer. A properly welded stud rings. A bad weld sounds dead and will fail under load.
For shells thinner than 6mm, verify that the stud welding heat does not distort the shell plate. If the shell bows between studs, the module backing plate will not seat flat, and hot gas will bypass the lining.
Step 2: Apply Module Gasket or Backing Material
Some installations call for a thin gasket - usually 3-6mm ceramic fiber paper or a high-temperature sealing compound - between the module backing plate and the steel shell. This gasket fills small irregularities in the shell surface and prevents gas bypass behind the module. Install the gasket before mounting the module so it does not shift during module placement.
Step 3: Mount the Module and Tighten
Slide the module onto the refractory anchor studs and press it firmly against the shell. Install the nuts and washers - typically M8 or M10 stainless steel - and torque to the supplier's specification. Over-tightening crushes the module backing and can crack the compression frame. Under-tightening leaves the module loose enough to shift during service.
A good rule of thumb: tighten until the module backing plate makes solid contact with the shell (or the gasket layer), then add one quarter turn. If the supplier provides a torque value, follow it. If not, ask.
Step 4: Cut the Compression Straps - in the Right Order
This is the step that causes the most field damage.
Ceramic fiber modules are shipped under compression. When you cut the binding straps, the module expands toward its free-state thickness. The expansion direction is out from the backing plate - toward the hot face. If you cut all the straps on a large module at once, one side may expand faster than the other, twisting the module and creating uneven gaps at the edges.
Cut the straps in a specific order: start with the straps closest to the top of the module (in a vertical installation) or closest to an already-installed adjacent module. Let that side expand and seat against the adjacent module or the shell corner, then cut the remaining straps. This gives a tight, gap-free fit against neighboring modules.
Step 5: Seal the Joints
After all modules are installed and expanded, inspect the joints between modules. Any gap wider than 3mm needs sealing. Use strips of ceramic fiber blanket - cut slightly oversize - and compress them into the gap. Do not use loose wool for joint sealing on the hot face; it compacts over time and leaves the gap open again. Compressed blanket strip is the right material.
For furnace roof installations, pay extra attention to the joints at the perimeter where modules meet the wall lining. These edge joints are vulnerable to gas bypass and should be packed firmly and inspected before the furnace is closed up.
Step 6: Inspect Before First Heat-Up
Walk the entire lining before the dry-out cycle starts. Check for:
Loose nuts on any module
Gaps wider than 3mm at any joint
Module edges that have not fully expanded (still partially compressed)
Damage to module surfaces from scaffold contact or dropped tools
Cleanliness - remove any debris that fell behind or between modules
Take photos of the completed lining from multiple angles. If there is a problem after start-up, you will want the baseline reference.
Dry-Out: The Step That Determines Module Life
Ceramic fiber modules contain a small amount of organic binder that burns out between 200°C and 400°C. The dry-out schedule must hold at these temperatures long enough for the binder to burn off gradually. A typical dry-out schedule runs:
Ambient to 150°C: Heat at 20°C/hour, hold for 4 hours
150°C to 350°C: Heat at 10°C/hour, hold for 8 hours (binder burnout zone)
350°C to operating temperature: Heat at 30-40°C/hour
Rushing through the 200-400°C band traps combustion gases inside the module, causing internal pressure that can delaminate the layers. If you have ever seen a ceramic fiber module surface peeling off in sheets after the first heat-up, the dry-out was too fast.
Getting Installation Support for Your Project
Every module supplier should provide an installation drawing showing stud layout, orientation, and torque values. A supplier who also offers remote support during installation - via WhatsApp video call or a technician on site - adds real value when the unexpected happens.
If you are planning a furnace reline and want installation guidance or a module specification that matches your operating conditions, contact us. We manufacture ceramic fiber blanket and modules under one roof in Zibo, Shandong, and have supported furnace lining projects in over 50 countries.
inquiry@topower.tech | WhatsApp +86 191 5332 7338 - 23 years, 60,000 MT/year, ISO 9001 / TÜV / SGS / Intertek.
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