Corrosion & Coatings Failures On Buildings

 

The Photo above shows a plastisol coating disbonding from a poorly prepared galvanized substrate.

 

 

Who Are We?

Amtec Consultants Deal With All Coatings & Corrosion Associated with Commercial & Industrial Buildings

Large structures ( such as storage tanks & bridges) have particular corrosion problems brought about by their size and location. Often corrosion or coatings failures occur because of adverse climatic conditions which occur during their construction process. Failures can be a result of air borne contamination or pollution during the prefabrication stage or during erection.

Paint cracking, star cracking (an example of which is shown above) or blistering commonly result. Often paint cracks only occur sometime after application due to the material loosing elasticity. Mud Cracking of the type shown below is commonly associated with over thick or over thinned coatings.

Corrosion driven by differential aeration cells or long distance galvanic effects are common. Where there is ground contact or stagnant conditions then microbial corrosion can occur.

Building Corrosion & Coatings Failures.

 

Coating breakdown on industrial buildings and structures can be carried out using a range of techniques, depending upon the clients’ requirements. Coating failures on factories, offices and housing units, including tower blocks, can be undertaken by Amtec’s Coating Engineers. Often industrial buildings suffer from cosmetic corrosion problems of the type shown in the above photograph. Commonly rust staining occurs as a result of aggressive conditions within the structure itself which then causes the rust to run down the outside.

We can ana lyse samples of paint to identify old paint types and provide information on the compatibility of old and new paints as well as identifying the causes of incompatibility and paint failure.

Paint 7 corrosion defects on new structures can be investigated, as can paint failures on railway, airport, terminals and hangars, together with coating failures on port and harbour buildings, hospitals and sports halls.

Amtec can investigate guarantee claims on paint and coatings on public, municipal, historic and listed buildings. We can also advise on the causes & repair of coating breakdown on sectional, framed and modular buildings including new, refurbished and old buildings.

Coated Cladding Failures.

In the photo above, & also in the photo of the red coating at the start of this page, the coating has suffered a catastrophic adhesion failure from the galvanized substrate. This kind of failure of plastisol coatings is relatively common & is due to poor surface preparation during manufacture. It tends to happen after 10-15 years & then progresses rapidly once the environment has penetrated along the coating to metal interface. repair at this stage is possible if replacing the cladding is either too difficult or too expensive.

 

In the photo above an aggressive environment has penetrated into the gap between the outer cladding and the insulation to develop a micro-climate. Usually the coating on the inside of the clad sheet is much thinner & less protective than that on the outside & corrosion can progress rapidly. The corrosion of the galvanized steel structure to white rust also indicates the severity of the environment.

 

The photo above clearly illustrates the inferior properties of the coating on the interior side of clad steel. The epoxy coated steel support structure is in excellent condition when compared to the very thin coating on the cladding.

Powder Coated preformed panels in aluminium tend to behave very differently & fail from edges by filiform & blistering mechanisms.

Coated Soffit Failures.

Soffits both under roof edges and above recessed window frames tend to be high humidity areas and breakdown earlier than other areas of the structure. These ares also tend to be sheltered from the rain & are not washed down regularly. Both the rust spotting shown above & coating blistering can develop early on in the service life of the structure if regular washing of the surface is not carried out.

Window Frame Corrosion & Paint Failures.

Window frame failures tend to differ greatly between types. Powder coated aluminium frames behave differently to galvanized steel frames.

Powder Coated Window Frames

Window frames usually fail at joints & edges. The reasons for this often revolve around either poor surface preparation or poor surface coverage of the coating in these areas. In general aluminium frames perform much better than steel frames when they are powder coated. This is because the surface preparation tends to be better and the corrosion products of aluminium are more benign towards coatings. Filiform corrosion from cut edges is the most common failure mode for aluminium frames. This can then lead on to full coating disbonding in the manner shown below:-

 

Galvanised Window Frames

Galvanized window frames also tend to breakdown from edges & corners. In the photo above the zinc had not adequately penetrated into the gap between the two components.

In the photo below the thickness of the galvanizing was insufficient over the weld used to construct the frame:-

Where galvanized windows fail in service one of the repair options is to strip of the coating and build up the zinc layer either with a zinc rich paint such as Galvafroid or similar.

A second option is to flame spray zinc in the manner show below:-

 

Here great care has been taken to mask off the window glass. However if the spray is too far from the frame then there can be inadequate fusion of the zinc particles onto the substrate.

 

Listed Building Coating Refurbishment.

Old paint types often contain either red lead or white lead. Red lead paint has a characteristic appearance of the type shown in the picture above. These paint types are a significant problem with their removal & subsequent disposal. During removal they represent a health hazard if they are breathed or inadvertently ingested orally especially if the exposure is prolonged. Great care has to be taken with the fit up of any face masks & regular face & hand washing is required. Smoking & eating in the vicinity increases the risk of ingestion. All paint flakes & abrasive materials have to be disposed of as contaminated waste. Environmental agencies should be consulted before & during coating removal.

Corrosion of Building Components.

In addition to examining whole buildings, Amtec can investigate parts of the structure for corrosion of roof cladding, frames, panels, joists and structural members. We also assess rust and corrosion of balconies, ceilings, floors, rails and decks for both poor workmanship and faulty construction.

Corrosion of doors, partitions, porches, stairs and walls can also be investigated to find the cause of the problem. Corrosion of suspended ceilings, mezzanine floors and lifts can be assessed for public bodies, corporations and private individuals.

Amtec can investigate corrosion of stainless steel and aluminium parts in buildings as well as corrosion and rust on window frames, curtain walls and metal tiles.

Coating Breakdown of Building Components.

If coatings are not properly applied onto sufficiently well prepared surfaces, coating failure and breakdown are likely to occur. Amtec can investigate the coating failure and provide impartial advice on the next steps.

We can investigate paint failure on roof, balcony, porch and deck components. Coating breakdown on cladding, panels, frames, partitions and doors can be ana lysed, as can coating breakdown on window frames, floors, steel, wood and plastic frames.

Paint failures such as blistering, bubbling, peeling, cracking and disbonding, can all be assessed. Coating failure on ceilings, hall ways, exterior and interior structures can be evaluated.

Corrosion of Building Fittings.

Corrosion of the fittings inside a building can easily occur if they are manufactured from the wrong type of material or they are stored or used under the wrong conditions. Amtec can investigate the corrosion of pipes, boilers, heat exchangers and plumbing parts. We can also assess rust and corrosion on joints, bolts, fixings, screws and fasteners.

Powder Coatings
Powder coated components can fail in service either as a result of poor mixing,application or surface pretreatment. Amtec have extensive experience of filiform corrosion failures & disbonding problems associated with the use of powder coatings in severe environments. Often the wrong type of powder coating has been specified for the environment. Epoxy powders tend to perform better than polyester coatings in severe environments. Epoxy polyester coatings also perform well.

 

Background.

Amtec have over 35 years experience of corrosion of industrial buildings and structures. We have carried out investigations into the corrosion of factories, offices and housing. Rust and corrosion on steel framed, sectional and modular buildings has also been carried out. We assess corrosion of listed, historic structures and buildings, anywhere in the world.

Amtec can also investigate the corrosion of warehouses, railway and airport buildings as well as corrosion of farms and sports halls and buildings. In addition, we evaluate corrosion on ports, hangars and terminal buildings, both old and new.

We also inspect corrosion of public and municipal buildings and can act as a joint expert for all parties involved or independently for one side, as required.

 

Reference Library.

A brief reference library is included in this site as an indication of some of our published work. Amtec consultants provide corrosion expertise in the field of metallic Corrosion. There are a series of Guides on our website dealing with a number of Corrosion & Coating Breakdown topics. Other pages are focused on areas such as marine corrosion, Industrial corrosion, Corrosion in Hot Water & heating Systems. Other guides deal with Aluminium Corrosion, Copper Corrosion & Stainless Steel Corrosion.

 

Free initial telephone guidance is available on all the topics covered on this web site.

e-mail enquiries sent to the address below will be promptly answered.