POLY·VAS Limited · Technical project development

Protection and rehabilitation of existing concrete tanks

What causes concrete tanks to deteriorate, and which protection method is suitable for an existing structure? The answer depends on the medium, the concrete, operating conditions and the rehabilitation method.

POLY·VAS develops and coordinates technical approaches for concrete tanks and containment structures in biogas, wastewater and industrial applications. We begin with the actual conditions of each project, not a predetermined product.

German origins · European experience · Kenyan base. The technical ideas originated in Germany. Practical experience extends across Germany, France, Austria, Italy, the Netherlands and Switzerland. POLY·VAS Limited is based in Nairobi, Kenya.

Artistically interpreted aerial view of an industrial biogas installation with circular storage tanks and access road
Industrial biogas installation · Artistic interpretation of a real facility

Understanding the structure

A tank may show visible loss of concrete, cracks, contamination or earlier coating failure. The first question is what caused the deterioration and how far it extends.

Any rehabilitation decision also has to consider tank geometry, access, temperature, the stored medium and the period for which the installation can be taken out of service.

Developing a suitable approach

Mineral protective systems, liquid-applied coatings, reinforced linings and mechanically fixed thermoplastics follow different construction principles. Material resistance alone does not decide which one is appropriate.

POLY·VAS assesses technical options, develops details, prepares material requirements and can coordinate suitable independent installation companies when a project justifies further work.

Why does concrete corrode in biogas tanks?

Hydrogen sulphide (H₂S), moisture and microbial processes can lead to biogenic sulphuric acid attack, particularly in the gas zone.

Where does the acid form?

Hydrogen sulphide formed under anaerobic conditions enters the gas space. On moist surfaces where oxygen is available, sulphur-oxidising microorganisms can produce sulphuric acid. It attacks the cement matrix and may cause material loss and cracking.

Is the damage only superficial?

Not necessarily. Chemical effects can extend beneath an apparently solid surface. The affected depth must be investigated for the particular tank.

Read the technical explanation

Why does the concrete surface matter for coatings?

Fully bonded coatings depend on a sufficiently sound, clean and appropriately prepared substrate.

What needs checking?

Surface strength, chemical contamination, moisture, condensation and required processing temperatures can affect adhesion and curing.

What changes with mechanical fixing?

A mechanically fixed lining reduces dependence on full-area adhesion but requires adequately sound concrete where it is anchored.

Compare the substrate requirements

Which rehabilitation methods are available?

Mineral systems, epoxy and polyurethane coatings, rubber, fibre-reinforced systems and thermoplastic linings have different strengths and limitations.

What determines suitability?

The medium, chemical exposure, temperature, mechanical load, existing concrete, joints and penetrations all need to be considered.

The method comparison explains the differences. TP·VAS is one mechanically fixed PP-H system, not the answer for every tank.

What happens when a tank expands and contracts?

Daily heating and cooling can move the concrete. The way a protective system is connected to the wall influences the stresses it experiences.

Fully bonded versus mechanically fixed

A coating bonded over its entire surface is coupled to the underlying concrete. A mechanically fixed thermoplastic lining is not rigidly bonded across the whole area; its own expansion and fixing details must nevertheless be designed properly.

Read about thermal movement

What determines rehabilitation downtime?

Surface preparation, drying, installation stages, curing, access and the condition of the structure can all affect the time before restart.

Why can mechanically fixed plates be faster?

PP-H plates do not require a completely dry, full-area adhesive substrate. Local sealing components, welding, safety and commissioning still have their own requirements.

Read about installation conditions

What is needed for an initial project assessment?

Start with what is known: structure, dimensions, stored medium, operating temperature, damage, photographs and project location.

What happens next?

We review the information and determine whether further technical evaluation is useful. A system recommendation, the possible project scope and the involvement of independent installation companies can only follow from that assessment.

See the information checklist below

TP·VAS – one defined system

TP·VAS combines mechanically fixed PP-H plates, fixing strips, an elastic contact layer, FPP welding bands and fully covered metallic fasteners. Its construction considers movement, accessible details and future repair.

Technical description in English · Deutsch

Project enquiries in the Gulf region

Local conditions and requirements are not assumed to be identical to those of European tanks. We request project information first and examine whether a suitable technical approach is possible.

Arabic headings · English explanations

Send information for an initial review

We need enough information to understand the structure before discussing a solution.

Structure and operation

  • Location and type of installation
  • Dimensions, drawings and construction type
  • Stored medium, temperatures and operating conditions

Damage and project constraints

  • Known defects, leaks and previous coatings
  • Photographs and earlier inspection reports
  • Accessibility and proposed shutdown period

Contact: info@poly-vas.com

This is an invitation to technical assessment, not a promise of a particular system or local availability.