TIF Tanks - Totally Internally Flanged GRP Sectional Water Tanks
Tricel manufactures TIF (Totally Internally Flanged) GRP sectional water tanks for restricted plant rooms and retrofit projects where standard EFB or IFB tanks cannot fit. All panel flanges, fixings and bolts are internal. The tank is assembled from within by Tricel-trained operatives — approximately 50mm clearance on three sides is all that is needed.
- •All flanges, fixings and bolts are internal, minimal external perimeter clearance needed on three sides
- •Assembled from within by Tricel-trained, confined-space-qualified operatives
- •Custom designed per project — not a stock item; engage Tricel early
- •NSF Regulation 4(1)a certified for potable cold water storage
TIF Tank — Key Specification
Flanging type
Totally Internally Flanged
3-side clearance
~50mm (indicative)
Pipework-side clearance
~500mm
Assembly
From inside - trained operatives
Maximum height
3m
Panel size
1,000 × 1,000mm standard
Internal fixings
Stainless steel 316
Certification
NSF Reg. 4(1)a — potable water
What is a TIF tank?
A TIF tank (Totally Internally Flanged tank) is a type of GRP sectional cold water storage tank in which all panel joint flanges, fixings and bolts are located on the inside of the tank structure. It is assembled from within by trained operatives, removing the need for external perimeter clearance on three sides during construction. TIF tanks require approximately 50mm clearance on three sides and approximately 500mm on the designated pipework access side — making them the most appropriate choice for highly restricted plant rooms, retrofit projects, high-rise buildings, healthcare estates and any installation where EFB or IFB sectional tanks cannot be accommodated. Tricel Water UK manufactures TIF GRP sectional tanks that are custom-designed per project, NSF Regulation 4(1)a certified for potable cold water storage, and available with stainless steel 316 internal fixings. Maximum height is 3 metres.
01
Definition
What Is a Totally Internally Flanged (TIF) Tank?
A Totally Internally Flanged tank is a GRP sectional cold water storage tank in which every panel joint — base, sides and lid — is flanged and bolted from inside the assembled tank. No external bolts, flanges or fixings appear on the exterior faces of the tank once it is built.
All installation operatives work from within the growing tank structure rather than around its exterior. The tank can be positioned immediately adjacent to walls, columns or existing plant on three sides. Only the single designated pipework and maintenance access side requires the standard working clearance of approximately 500mm.
TIF tanks use the same GRP panel production, certifications and standard 1,000 × 1,000mm panel sizes as the EFB and IFB range. The difference is entirely in the flanging system, the assembly sequence and the clearance requirements that result. EFB and IFB tanks should be specified wherever clearance allows — TIF is the right choice only when those options are ruled out.
Custom designed — not a stock item. Every TIF tank is designed and manufactured for a specific project. Engage Tricel early with plant room dimensions, access route details and required capacity to allow the design and programme to be planned. Lead times are longer than for one-piece or standard EFB tanks.
TIF vs Standard Sectional — Core Difference
The following is indicative guidance only. Each project should be assessed individually at design stage.
EFB / IFB — assembled from outside
- Side panel flanges on external face
- Operatives work around the outside
- ~500mm clearance all sides required
- Up to 4m high — self-draining option (EFB)
TIF — assembled from inside
- All flanges internal — no external fixings
- Operatives work inside the tank
- ~50mm three sides / ~500mm one side
- Up to 3m high — pump required to drain
02
The 50mm Clearance Advantage
Why ~50mm Clearance on Three Sides Changes Everything
Standard EFB and IFB sectional tanks require approximately 500mm perimeter clearance on all four sides to allow operatives to access external fixings during assembly. In a congested plant room, basement, or retrofit where existing services, columns or walls occupy that space, this is often prohibitive.
The TIF configuration removes this barrier on three sides. Because every fixing is inside the tank, it can be positioned within approximately 50mm of walls, columns or adjacent equipment on three sides — occupying the maximum available footprint while leaving only the pipework access side
~50mm and ~500mm are indicative design guidance values for planning purposes only. They must be confirmed at design stage for each project. Maintenance access, inspection requirements and confined space provisions must be addressed separately in the installation design.
No external scaffold or temporary platforms — all assembly work is from inside, reducing programme time and cost on constrained sites
Existing services and plant can remain in place — the working zone during installation is confined to the tank interior and the single access side
Enables retrofit where other configurations cannot go — TIF makes it possible to achieve the required storage capacity in rooms that would otherwise force a compromise
Accommodates structural imperfections — the ~50mm gap allows for slight deviations in wall face, column profile or floor level common in older and retrofitted buildings
03
Assembly Process
How a TIF Tank Is Assembled
TIF assembly is the reverse of the standard sectional process. Rather than working around the outside, Tricel-trained operatives work progressively from inside the growing tank structure. This makes the ~50mm three-side clearance possible — and it requires specific training and confined space working procedures throughout.
Survey, access confirmation and base preparation
Plant room dimensions, access route, pipework side, base condition and headroom are confirmed before manufacture begins. The base — typically a flat concrete slab with galvanised levelling steels — is prepared to 2mm/1m flatness tolerance. Getting this right before panels arrive eliminates the most common causes of programme delay on TIF projects.
Panel delivery through the available access route
Individual GRP panels are palletised and transported to site. Each panel passes through the available access route — standard doorways (750mm clear minimum for 1m panels), stairwells, goods lifts or roof hatches — to the installation position. The 1,000 × 1,000mm panel size is specifically dimensioned to pass through normal building access routes.
Base panels positioned on levelling steels
Base panels are laid onto the levelling steels. All base flanges are internal — the panels can be positioned without any working clearance on the outside of the footprint. Alignment is confirmed at this stage before side panels are built up.
Progressive side panel assembly from inside the tank
Side panels are added progressively. At each stage the operative enters the part-assembled tank to install the internal fixings on the newly added panels. This is the defining step of the TIF process: the entire fixing and sealing operation takes place from inside. No external clearance is required on the three constrained sides. Confined space entry procedures apply from this point onwards.
Lid panels installed
Lid panels are fitted last with internal fixings, completing the tank. The 800 × 800mm access hatch remains accessible for all subsequent inspection, cleaning and maintenance. Hatch position is confirmed at design stage.
Pipework connections on the designated access side
All connections, float valves, overflows and drain points are installed on the designated pipework access side (~500mm clearance). This side is fixed at the design stage — it cannot be changed after manufacture. Confirm the pipework side at enquiry stage, not after the order is placed.
Commissioning, cleaning and handover
The completed tank is cleaned, disinfected, flushed and tested to BS EN 806-5. Handover documentation includes the Regulation 4(1)a certificate, as-installed drawings, commissioning record and BSA 2022 Golden Thread documentation where required by the project.
Tricel-Trained Installation Teams
TIF assembly requires operatives specifically trained in the internal assembly sequence. Tricel engineers are:
- CSCS certified
- Confined space trained and qualified
- Factory trained on Tricel products – not sub-contracted labour
- Experienced in restricted access and retrofit plant rooms across the UK
TIF assembly inside a part-assembled tank body constitutes confined space working under the Confined Spaces Regulations 1997. A risk assessment, safe system of work, entry permit and rescue arrangement must be in place before any operative enters. Tricel teams operate under established confined space protocols.
Tricel offers free site surveys subject to location. A survey before specification confirms access route, base condition, pipework side and clearance — preventing revisions at a later stage when the programme impact is greater.
04
Configuration Comparison
EFB, IFB and TIF — Choosing the Right Sectional Tank
All three configurations share the same GRP panel construction and certifications. The choice is determined entirely by available clearance, headroom and access. TIF is appropriate only when EFB and IFB cannot be accommodated.
Standard — open access
EFB — Externally Flanged Base
Assembly
Clearance needed
~500mm all sides
Base type
Raised on support steels
Self-draining
Yes
Max height
4m
Specify when
Open access / standard plant room
Limited headroom
IFB — Internally Flanged Base
Assembly
External sides; internal base
Clearance needed
~500mm all sides
Base type
Flat plinth or levelling steels
Self-draining
No – pump required
Max height
4m
Specify when
Limited headroom; standard clearance
Restricted access — this page
TIF — Totally Internally Flanged
Assembly
Internal — from within tank
Clearance needed
~50mm × 3 / ~500mm × 1
Base type
Flat base / levelling steels
Self-draining
No — pump required
Max height
3m
Specify when
EFB / IFB perimeter cannot be met
|
Feature
|
EFB
|
IFB
|
TIF
|
|---|---|---|---|
|
All flanges internal
|
No
|
Base only
|
Yes — all panels
|
|
Three-side clearance
|
~500mm all sides
|
~500mm all sides
|
~50mm three sides
|
|
Max height
|
4m
|
4m
|
3m
|
|
Self-draining
|
Yes — raised base
|
No
|
No — pump required
|
|
Confined space during assembly
|
Not required
|
Not required
|
Yes
|
|
Reg. 4(1)a certified
|
Yes
|
Yes
|
Yes
|
|
Retrofit suitability
|
Where clearance allows
|
Where clearance allows
|
Highly suited
|
|
Specify when
|
Default for open access
|
Restricted headroom
|
Insufficient perimeter clearance for EFB/IFB
|
05
Applications
Where TIF Tanks Are Specified
TIF tanks are specified where available plant room clearance or building access prevents an EFB or IFB installation. The following building types and scenarios most commonly generate the conditions where TIF is the right choice.
Healthcare & NHS
High-Rise & Multi-Storey
Infrastructure & Utilities
Fire Protection
Data Centres
Industrial & Manufacturing
Education
Agriculture
Food & Beverage
Local Authority & Public
The 3m maximum height for TIF tanks means that for very large storage volumes, a wider or longer footprint is needed. If this creates a footprint conflict, discuss alternatives with Tricel technical sales before committing to a configuration.
06
Technical Specification
TIF Tank Technical Specification
TIF tanks are manufactured using the same GRP panel production as the EFB and IFB range. The following values apply as standard unless otherwise confirmed for the specific project.
Flanging
Totally Internal
All panels — base, sides & lid
3-side clearance
~50mm
Indicative — design confirm
Pipework side
~500mm
1 side — fixed at manufacture
Max height
3m
Hand lay-up production
|
Parameter
|
Specification
|
|---|---|
|
Configuration
|
Totally Internally Flanged — all bolts internal
|
|
Panel size (standard)
|
1,000 × 1,000mm
|
|
Internal fixings
|
Stainless steel 316 throughout
|
|
Man-way (access hatch)
|
800 × 800mm opening as standard
|
|
Clearance above man-way
|
500mm minimum for ongoing access
|
|
Three-side clearance
|
~50mm (indicative — confirm at design)
|
|
Pipework access side
|
~500mm — confirmed before manufacture
|
|
Maximum height
|
3m
|
|
Foundation
|
Flat, level, structurally capable base with galvanised levelling steels
|
|
Base flatness tolerance
|
2mm per 1m / 6mm per 6m
|
|
Insulation (where specified)
|
38mm fully encapsulated to sides and lid
|
|
GRP construction standard
|
BS EN 13280:2001
|
|
Certification
|
NSF Regulation 4(1)a — potable cold water storage
|
|
Drainage
|
Pump or sump required — cannot self-drain
|
|
Design basis
|
Custom designed per project — not a standard stock item
|
Critical design considerations specific to TIF
Confirm these before specifying
- Pipework side— must be identified before manufacture. All connection positions are fixed at fabrication and cannot be changed.
- Max height 3m— for large volumes this requires a wider or longer footprint. Confirm the panel configuration achieves the required nominal capacity before ordering.
- Hatch clearance— 500mm above the man-way must remain unobstructed throughout the life of the tank for inspection, cleaning and confined space entry.
- Drainage— TIF tanks cannot drain fully by gravity. A sump or pump must be specified in the mechanical design.
- Confined space maintenance— the 800 × 800mm hatch is the only entry/exit point for ongoing maintenance. Confirm it is accessible from the access side at all times.
Tricel provides free specification support including TIF configuration advice, capacity calculation and plant room layout review. Email websales@tricelwater.co.uk or call +44 (0)1934 421 499.
07
Installation Planning
TIF Tank Installation — Key Checks
A site survey before specification avoids the most common causes of programme delays. These checks can mostly be answered by measuring the plant room and walking the full access route.
|
Check
|
Requirement
|
Why It Matters
|
|---|---|---|
|
Panel access route
|
Doorways ≥750mm clear for 1m panels
|
Measure all doorways, stairwells, lift dimensions and corridors on the full delivery route
|
|
Base condition
|
Flat, level, structurally capable
|
2mm/1m and 6mm/6m tolerance. Levelling steels typically supplied with the tank
|
|
Pipework side
|
~500mm clear — confirmed before order
|
All connections are on this face. Fixed at manufacture — cannot be changed post-build
|
|
Three-side clearance
|
~50mm (indicative — design confirm)
|
Check for protruding elements, pipes or equipment on the three constrained sides
|
|
Headroom
|
Panel height + 500mm above man-way
|
Check that roof beams, overhead pipes and services do not intrude into the clear height
|
|
Max height constraint
|
3m maximum for TIF
|
If greater headroom is available, TIF can still be used at 3m — larger footprint may be needed for volume
|
|
Drainage
|
Pump or sump required
|
TIF cannot drain by gravity. Drainage strategy must be confirmed in the mechanical design
|
|
Confined space provision
|
Risk assessment and safe system of work
|
Required for assembly and all future maintenance inside the assembled tank
|
All clearance values are indicative design guidance only — not regulatory requirements. Confirm all values against the specific project configuration, tank dimensions and maintenance strategy at design stage.
08
Project Experience
TIF Tank Project Experience
Tricel has installed TIF tanks across healthcare, commercial, high-rise and infrastructure projects where plant room constraints made EFB or IFB unsuitable.
Data centre — TIF sectional cold water tank
Totally internally flanged (TIF) sectional GRP cold water storage tank installed in a data centre to maximise capacity within a constrained plantroom. Designed with twin compartments for compliance with HSE ACoP L8 and ease of maintenance.
Commercial office building — bespoke C-shaped TIF tank
Football stadium — 6000 litre TIF tank
6000 litre totally internally flanged (TIF) GRP tank installed at a football stadium to supply sprinkler systems, engineered to suit unconventional dimensions and ensure reliable water storage on site.
09
Technical Downloads
TIF Tank Technical Resources
Technical documents for M&E engineers, specifiers, project managers and facilities managers.
GRP Sectional Tank Product Brochure
Overview of EFB, IFB and TIF configurations, capacity ranges, approvals and specification options.
TIF Tank Technical Brochure
Detailed technical specification for TIF (Tank Internally Flanged) GRP sectional tanks for constrained plant rooms.
IFB Tank Technical Brochure
Specification summary for IFB internally flanged base tanks, covering design and application.
10
Specification Support
Request a TIF Tank Quote or Site Survey
TIF tanks are custom designed. Providing plant room dimensions, access route details, required capacity and the proposed pipework side allows Tricel to produce a meaningful quotation and identify constraints early.
Information needed for a TIF tank quotation
Plant room dimensions (L × W × H)
Access route — doorways, stairwells, lifts
Base condition and construction type
Insulation requirement
Certification requirements (Reg. 4 / WRAS)
Plant room drawings or as-built layouts
Required storage capacity (litres)
Proposed pipework side (N/S/E/W)
Existing services positions if constraining footprint
Potable or non-potable duty
Existing tank details (if retrofit)
Required programme and delivery timescale
Request a quote or site survey
Send plant room dimensions, access route details and required capacity. Tricel will confirm whether TIF is the right configuration, provide a quotation and arrange a free site survey where appropriate.
Where access prevents a TIF tank and volume cannot be achieved within the 3m height limit, Tricel can advise on L-shaped tank configurations or other approaches. Raise this at the enquiry stage.
11
Related Products & Resources
Sectional Tank Range & Related Resources
TIF tanks are part of Tricel’s GRP sectional tank range. These resources support specification, sizing and compliance across the full range.
Sectional Tank Configurations
Compliance & Aftercare
12
FAQS
TIF Tank FAQs
Common questions from M&E engineers, specifiers and project managers.
What is a TIF tank?
A TIF tank (Totally Internally Flanged tank) is a GRP sectional cold water storage tank in which all panel joint flanges, fixings and bolts are on the inside of the tank structure. It is assembled from within by trained operatives, requiring approximately 50mm clearance on three sides and approximately 500mm on the pipework access side. TIF tanks are suitable for highly restricted plant rooms, retrofit projects and installations where standard EFB or IFB tanks cannot fit.
What does TIF stand for in water storage tanks?
TIF stands for Totally Internally Flanged — a GRP sectional water tank configuration in which all panel flanges, joint fixings and bolts are on the inside of the structure, so no external perimeter clearance is required on three sides during assembly.
How much clearance does a TIF tank need?
As indicative design guidance, approximately 50mm clearance on three sides and approximately 500mm on the pipework access side. A minimum of 500mm above the man-way height is also required for ongoing access. These are indicative values that must be confirmed at design stage for each specific project.
What is the difference between TIF, IFB and EFB tanks?
EFB tanks have external side flanges, require ~500mm clearance all sides and are self-draining from a raised base. IFB tanks have an internal base flange but external sides, require ~500mm all sides and need a pump to drain. TIF tanks have all flanges internal, require only ~50mm on three sides and ~500mm on one, are assembled from within and need a pump to drain. EFB and IFB reach 4m; TIF is limited to 3m.
What is the maximum height of a TIF tank?
Tricel TIF tanks are available up to a maximum height of 3 metres. EFB and IFB configurations reach 4 metres. For large storage volumes within the 3m constraint, a wider or longer footprint may be needed. Confirm this at design stage.
Are TIF tanks Regulation 4 certified?
Yes. Tricel TIF tanks carry NSF Regulation 4(1)a certification for potable cold water storage. WRAS-compatible configurations are also available. Confirm certification status at the quotation stage as it depends on the full specification.
When should I specify a TIF tank instead of EFB or IFB?
Specify TIF when available perimeter clearance is insufficient for EFB or IFB assembly and when a one-piece or two-part tank cannot be delivered. TIF is appropriate for restricted plant rooms, retrofit, high-rise buildings, healthcare estates and dense urban sites. EFB and IFB should be specified wherever clearance permits — both offer simpler assembly and EFB offers self-drainage.
Can TIF tanks be installed in basements or underground plant rooms?
Yes. Individual 1,000 × 1,000mm panels can be transported through stairwells and narrow corridors before being assembled inside the plant room. All clearance, access route and headroom requirements must be confirmed at design stage before panels are ordered.
What information is needed to specify a TIF tank?
Available plant room dimensions (L × W × H); access route details; required storage capacity; proposed pipework side; base condition; insulation and certification requirements; existing tank details if retrofit. Plant room drawings are particularly helpful. Contact Tricel on +44 (0)1934 421 499 or websales@tricelwater.co.uk.
UK GRP Tank Manufacturer — Custom TIF Design
Specify a Tricel TIF tank for your restricted plant room
Send your plant room dimensions, access route details, required storage capacity and proposed pipework side. Tricel will confirm whether TIF is the right configuration and provide a quotation and site survey.
This product guide is provided for general guidance and information purposes only. It does not constitute engineering advice and should not be relied upon as the sole basis for design decisions. © 2026 Tricel Water. All rights reserved.
