Mechanical Technology

Mechanical Technology — October 2015

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Structural engineering materials, metals and non-metals

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About Belzona

Established in 1952, Belzona has pioneered

innovative polymer technology that has revo-

lutionised industrial repair and maintenance

procedures.

The company is a leader in the design

and manufacture of polymer repair com-

posites and industrial protective coatings

for the repair, protection and improvement

of machinery, equipment, buildings and

structures.

The full Belzona product range is manu-

factured in Harrogate, England, to stringent

quality and environmental control guidelines

to comply with the requirements of ISO

9001:2008 and ISO 14001:2004.

As well as AESSEAL in South Africa,

Belzona has over 140 distributors in more

than 120 countries ensuring not only the

availability of Belzona materials, but also

specification support, project manage-

ment, application and supervision services.

Distributorships and their teams are sup-

ported by Belzona Corporate offices in

Europe, North America and Asia.

About AESSEAL

AESSEAL is a specialist in the design and

manufacture of mechanical seals and sup-

port systems.

The company’s mechanical seals are

used in a wide range of pumps and rotat-

ing equipment worldwide to prevent liquids

and gases escaping into the environment.

AESSEAL manufactures mechanical seal

types to suit all industries and its investment

in modular designs means that it can provide

the best on-time delivery performance in

the industry.

The AESSEAL range of seals, seal sup-

port systems and bearing protectors are all

designed to improve pump reliability and

reduce maintenance costs. The business is

built around giving customers such excep-

tional service that they need never consider

alternative sources of supply.

AESSEAL operates from 230 locations in

104 countries, including nine manufacturing

and 58 repair locations, and has more than

300 customer service representatives who

visit industrial plants every day.

Figure 3: A paste grade epoxy material was chosen to fill the pits and

afterwards, the wall was protected with a modified epoxy novolac coating.

Figure 4: In July 2015, after four years in service, the reboiler was again opened

up for inspection. No further pitting damage or corrosion was identified.

should be ground down to a smooth

contour with a radius of not less than

3.0 mm. All surfaces must then be grit

blasted using an angular abrasive to

Swedish Standard SA 2½ (near white

metal finish) with a minimum profile

of 75 microns.

4. Paste grade epoxy material must be

mixed in the correct ratio.

5. The material needs to be applied onto

the substrate until the original wall

thickness is restored.

6. The material must be allowed to so-

lidify at ambient temperatures before

achieving full cure in service.

One drawback traditionally associated

with the use of epoxy materials for pit-

ting repairs has recently been overcome,

namely the amine bloom film that would

appear on the surface during curing. The

bloom would manifest in the form of

sticky deposits that affected overcoat-

ability and intercoat adhesion. It had to

be removed by first washing with a hot

detergent solution followed by a fresh

water wash, and then frost blasting prior

to the application of a protective coating

on top of the pitting repair, leading to ex-

tended application time and labour costs.

The latest innovation in raw materials

has brought on non-bloom technology,

where frost blasting of the applied mate-

rial prior to the application of protective

lining is not required. This feature was

incorporated into the reformulated ver-

sion of the Belzona 1511 (Super HT-

Metal), which has been on the market

since 2001. In addition to incorporating

non-bloom technology, further evaluation

revealed the following enhanced features:

• Frost blasting of the Belzona 1511 is

no longer required when a protective

lining is being applied on top with a

24-hour overcoat window, thus reduc-

ing application costs.

• Application is also simplified with

mixing and application possible at

temperatures as low as 10 °C (50 °F).

• The rubbery domains used in Belzona

1523 and Belzona 1593, which were

also incorporated in the polymer ma-

trix of Belzona 1511, have improved

the adhesion, flexibility and toughness

of Belzona 1511. Tensile shear adhe-

sion (ASTM D1002) has increased by

46% regardless of the cure tempera-

ture. Pull off adhesion has increased

by 34% (ASTM D4541/ ISO 4624).

Continuous advancements in raw ma-

terials make it possible for coating and

composite manufacturers to produce

systems that are better value and easier

to apply, at the same time minimising

the risks typically associated with hot

work. In this way, the indirect costs of

corrosion, including downtime, delays,

litigation and other unplanned overheads,

can be significantly reduced.

Belzona compounds are distrib-

uted and supported in South Africa by

AESSEAL.