By Marcio Bomfim Dessaune, Mechanical Engineer and Managing
Director; and Carlos Llanes Leyva, Mechanical Engineer, Master of
Science, Engineering Director of Braco Consultants, Vitoria — Brazil.
 
ABSTRACT
Due to the increasingly globalized nature of the bulk material
handling business, fundamental decisions that once were made
based on localized requirements are now more frequently being
addressed based on international standards, codes, and
expectations. The reason for this is that capitalization costs and
O&M costs are now being looked at through the lens of total
installed, lifetime costs. When these factors are added together
the simple selection of which standard to use, if there is an
option, becomes very important to that elusive total installed,
lifetime cost. One of the very first decisions facing an owner,
engineer or contractor is to ‘standardize’ on belt widths and
design criteria as defined by CEMA — Conveyor Equipment
Manufacturers Association (inches) or ISO — The International
Standardization Organization (millimetres).
The main points of this article are:
  Follow a standard. Avoid creating company standards that
take exception to the standard selected.
  Select either the CEMA or ISO standard unless there are
extenuating circumstances — like local codes that must be
followed. Either standard is very good and neither one is really
better than the other.
  Don’t mix different standards initially or in future work.
  Keep in mind that once you have selected a standard there
are other derived standard dimensions that will help during the
design process.
  The standard belt widths for both standards are provided
here. Widths not shown are not standard.
The article outlines some of the differences between these
two standards as well as some other standards in use around
the world. It also provides suggestions for proper selections
within each standard.
 
GENERAL COMMENTS
All conveyor design generally complies with quality standards
established by company, local, national or international
authorities. These governing authorities vary widely from
company to company, local area to local area as well as country
to country and these localized standards sometimes comply with
international standards but oftentimes the international standard
is only used as a point of reference.
It’s important to understand that when selecting something as
seemingly simple as conveyor belt width, these various standards
may have impacts on operations and maintenance well after the
time of initial installation. When a standard is adopted, various
other derived standards are implied or even expected.
Consequently, a wrong choice at this early stage may lead to
higher design, operating and maintenance costs later
 
COMMON INTERNATIONAL STANDARDS
The American (CEMA), Japanese (JIS) and German (DIN)
standards are quite well known worldwide. Other countries
such as Brazil (ABNT), and many others generally follow the
recommendations of ISO.
Although some of these standards are not specifically belt
width standards, the standardized belt width properties are
listed as part of the standard. In most cases, the ISO or CEMA
standards are selected, the ISO being in millimeters, the CEMA
being in Imperial units. The Japanese standard JIS uses a variation
of the ISO but adds widths in millimetres that are not specified
in ISO.
 
STANDARD BELT WIDTHS
For reference purposes, the table above lists the various belt
widths in use and as identified by the standards indicated. Belt
widths omitted are not considered to be ‘standard’ by the
reference code:
Note: Larger widths not shown in the table above are in use. In
these cases, the widths follow the same general relationships shown
above but are not necessarily, ‘standard’.
 
MIX AND MATCH AT YOUR FUTURE EXPENSE
A steel mill in Brazil that was initially built in the early 1980s was
designed under the influence of reference standards from Brazil,
CEMA and ISO. This led to the usual conflicts among design
codes however there was no decision made to select conveyor
belt widths based on any one standard. As a result, widths were
selected for belts to match required design capacities in both
metric and Imperial units. For any given required conveyor
capacity (tonnage per hour) the belt widths chosen were
selected based on the requirements of the code in use — per
usual practice.
As the mill evolved, expanded, modified and changed,
additional conveyors were designed based on a ‘mix’ of
standards, all to match the required capacities of the flow sheets
in use. As a result this facility has a mix of belts in inches and in
millimeters. Later as this problem exacerbated the spare parts
situation and the need for various sizes to fit onto the same
conveyor line, the company decided to standardize on the
CEMA system. Consequently there are now strange (i.e. non
standard) sizes in use. The 56” and 80” non standard sizes belts
are in use plus some belt feeders that were kept in millimetres
as originally designed.
These non-standard belt widths and the need for all kinds of
different spare parts in order to have the right part on hand at
the right time has resulted in a nightmare of logistics and
warehousing not to mention the use of non-standard widths
requires on-site storage of belts that are not ‘on the shelf’ ready
for ordering from a supplier. This extends to pulleys, idlers, belt
cleaning equipment, skirt boards, engineered chutes, and virtually
every piece of equipment necessary to keep a conveyor in
continuous use. The lesson learned? Standardize early, and stick
with it!
 
IMPACTS OF STANDARD SELECTED
It must be kept in mind that belt widths will affect some other
important components and design considerations. Some of the
more noteworthy:
  •   pulley widths;
  •   idler dimensions;
  •   stringers of the idler supporting frame distance;
  •   chute work and stringer dimensioning;
  •   belt scrapers, ploughs, cleaners;
  •   bearing centre to centre distances.
Other considerations come into play as well. For example,
the fact that a 1,500mm width belt is being used does not mean
that the metric standard is being adopted. ISO standards call for
a 1,400mm or a 1,600mm width. A 1,500mm belt width is not
standard so a 60 inch belt (1,524mm) is called for — which
means a CEMA standard not an ISO standard!
 
RECOMMENDED BELT WIDTHS
The table above, right, provides a listing of belt widths in either
standard that are in common use today. Widths not shown
should not be considered to be ‘standard’ with all the attendant
ramifications for extra cost, long lead times, and lack of local
spare parts that are readily available. The table shows the
approximate equivalence between the two standards:
 
 
CONCLUSION
During the conceptual design of a belt conveyor project, it is
important to decide which design standard should be used and
to stick with it in the future. The metric system (ISO Standard)
or the imperial system (CEMA Standard) have competing
standards that result in very similar design considerations. The
decision however has far reaching impact on not only the initial
design but future costs and maintenance considerations. By no
means should these standards be mixed as this brings additional
spare parts and maintenance costs to an owner that is not
always anticipated at the outset of the site facility planning.
The widths provided by in the table above — imperial or
metric — should be used for the most efficient cost picture for
most international facilities.
 
BIBLIOGRAPHY
  •   CEMA, Belt Conveyor for Bulk Materials, Fifth Edition, ISBN1-891171-18-6, USA.
  •   CEMA STANDARD NO. 502-1996, Bulk Material Belt Conveyor Troughing and Return Idlers, USA.
  •   ISO 251, Conveyor belts – Widths and lengths, Second Edition, International Organization for Standardization.
  •   NBR 6110, Transportadores contínuos – Transportadores de correia – Larguras de correias transportadoras, ABNT (Brazilian national standard), September 1993.
  •   JIS B 8803, Rollers for belt conveyors, JIS (Japanese Industrial Standard), 1990.
  •   DIN 22102 – Part 1, Conveyor belts with textiles plies for bulk goods: dimensions, specifications, marking (German national standard).