Can an Old Bolted Tank Be Raised in Height
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Can an Old Bolted Tank Be Raised in Height?
One of the quiet advantages of a bolted tank is that it can grow. Because the shell is built from stacked, bolted panel courses rather than a welded cylinder, raising the tank means adding more courses on top of the existing wall - no cutting, no on-site welding of the shell, no lost coating inside. A welded tank, by contrast, is a continuous cylinder; making it taller means cutting and re-welding, which also disturbs the internal lining. So the question 'can we add capacity later?' has a much cheaper answer for bolted construction.
Shijiazhuang Zhengzhong Technology Co., Ltd. (Center Enamel) has raised existing bolted GFS tanks by adding panel courses, provided the original foundation, anchorage and roof were specified with future height in mind - which is exactly why reserving capacity at design stage pays off.
1. How the Height Is Increased
The process is additive: the roof is lifted or temporarily removed, one or more panel courses are bolted onto the top of the existing shell using the same Grade 8.8 bolts and sealant, and the roof is re-fitted. Because every panel is factory-coated before delivery, the new courses arrive with their enamel intact, so the extended tank has a uniform, continuous lining with no on-site recoating of the shell.
· Add Courses: Bolt new panels on the shell top.
· Same Bolts: Grade 8.8 and certified sealant.
· Factory-Coated: New panels arrive enameled.
· Uniform Lining: No on-site shell recoat.
· Roof Refitted: Lifted, extended, replaced.
2. What Must Be Checked First
Not every tank can be raised. The original foundation must carry the extra shell and water load, the anchorage must hold the taller, more exposed wall under wind, and the roof must be compatible with the new height. The existing panels and sealant must also be sound. Skipping this check is the main way a raise goes wrong - the shell may be fine while the foundation is not.
· Foundation Load: Carries extra shell and water.
· Anchorage: Holds taller wall in wind.
· Roof Fit: Compatible with new height.
· Panel Soundness: Existing wall must be good.
· Do the Check: Shell fine, foundation may not be.
3. Why Bolted Beats Welded Here
A welded tank raised in height must be cut, welded and then have its internal coating repaired or replaced in the disturbed zone - work that stops the tank and risks the lining. A bolted tank avoids all of that: the new material is pre-finished and simply bolted on. The comparison is not close when the goal is adding height without taking the tank out of service.
· No Shell Cutting: Bolted adds, welded cuts.
· No Recoat: New panels are pre-finished.
· Stays in Service: Less downtime to raise.
· Cleaner Lining: No disturbed coating zone.
· Lower Risk: Fewer site welds to inspect.
Design parameter | Typical value or range | Why it matters |
Bolt grade | Grade 8.8 | Same as original shell |
New courses | Factory-enameled | No site recoat of shell |
Foundation | Must carry extra load | Often the real limit |
Anchorage | Holds taller wall | Wind on taller tank |
Roof | Must fit new height | Check before raising |
Limitation to check | Shell may be fine, base not | Verify foundation first |
Option | Bolted GFS | Welded steel | Implication |
Raise height | Add panel courses | Cut and reweld | Bolted far simpler |
Lining impact | None, pre-finished | Recoat disturbed zone | Bolted keeps lining |
Downtime | Low | High | Bolted stays in service |
Foundation check | Required | Required | Same for both |
Future-ready | Designed in | Harder retro | Reserve helps bolted |
Engineering Assurance and Project Support
Every tank delivered by Shijiazhuang Zhengzhong Technology Co., Ltd. (Center Enamel) is engineered against AWWA D103-09 and EN 1090 with finite element verification of shell, roof and nozzle loads, fused at 820-930°C under ISO 9001 and ISO 45001 control, holiday tested at 1500 V across one hundred percent of the surface, and assembled with Grade 8.8 bolts and manufacturer-certified sealant. Raising is delivered with a re-check of the foundation and anchorage calculations, matched panel courses and sealant, and a lift plan for the roof, so the owner extends capacity with the same quality records as the original tank.
Yes, a bolted GFS tank is raised by bolting new, factory-enameled panel courses onto the existing shell - no cutting, no on-site shell recoating - an option a welded cylinder simply does not have. The non-negotiable step is checking the foundation, anchorage and roof first, because the shell may be ready while the base is not.
Frequently Asked Questions (FAQ)
How much can I add in one raise?
It depends on the foundation and anchorage margin left at the original build. A tank designed with reserve can often add one or two courses; a tank built to the absolute minimum cannot. The foundation calculation, not the shell, sets the limit.
Does raising disturb the internal coating?
No - the new courses arrive factory-enameled and the existing wall is untouched, so the lining stays continuous and holiday-spark verified. That is the core reason bolted raising is cleaner than welded cutting, which always disturbs the internal surface.
Will the roof still fit?
Only if it was specified for the taller tank or is adjustable. A fixed roof not designed for extra height will not seat correctly, so the roof compatibility check is part of the pre-raise review rather than an afterthought.
Can the raise be customized to my tank?
Yes. The added height, panel course count, anchorage upgrade, roof adaptation and sealant are configured to your existing tank and site loads, delivered with the recalculated foundation and lift plan.
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