Top 10 Tips - Hose Assembly

Posted by  Mark Carpenter 26-Feb-2014 10:26:00

Mark heads up our Industrial Hose Core Competence Centre


1. Respect your hoses and fittings.  Since they are often perceived as commodity items, few engineers spend a lot of time thinking about hoses and fittings.  As a consequence, they are often poorly specified and installed, then ignored once they have been fitted into machinery.  However, the incorrect selection of materials will typically lead to an unnecessarily rapid deterioration over time, while the wrong choice of hose fittings or clamps can result in a sudden and often catastrophic failure. 

2. Be aware of the dangers Hose failure can be hazardous to operating equipment and, more importantly, a major health and safety risk to employees.  It is important to note here that this danger is not only presented by high pressure hoses – typically above 25 bar – but also to hoses and fittings used in lower pressure applications, especially if they are carrying steam or hazardous chemicals.

3. Consider newly enhanced components. Advances in technology have brought engineers the option to specify bespoke industrial hose assemblies that are lighter and stronger, and can meet the needs of many different applications.  Bespoke assemblies can be provided that meet strict industrial hygiene standards to serve food and pharmaceutical applications, while exceptionally robust metallic hoses can be obtained where there is a need to withstand extreme high temperatures and pressures.

4. Match the fitting to the hose Wherever flexible industrial hose products are required, appropriate fittings are essential.  Only by making the correct specification to match the hose itself can engineers maintain the productivity and quality of the hose output.  Weather exposure and process conditions will significantly affect product lifespan, as will the pressure of the process fluid.

5. Specify correctly for low pressure.  O-clips and worm drives, often called ‘Jubilee clips’, are suitable for low pressure, aspiration and suction type hoses – typically below 4 bar – and are easy to fit and remove.  These components need to be used with relatively soft-walled hoses so that the clip can apply sufficient pressure on the inner wall of the hose to form an effective seal.  Careful installation is required here, as misalignment or over tightening may cause leaks. 

6. Specify correctly for high pressure.  In higher pressure applications, swaged or crimped connections offer an excellent degree of security, giving leak-free connections.  However, the fittings have to be formed using a special machine, requiring a qualified operator.  These connections work by deforming a metal ferrule and hose tail permanently into place around the end of each hose.  In many instances, the ferrule is designed to cut through the outer hose wall to interlock with the internal layers of wire hose reinforcement. 

7. Allow time for preparation When planning a hose installation it is important to bear in mind that, although swaged or crimped connections produce extremely reliable results, hoses have to be produced to order off-site.  This does not allow urgent repairs or replacements to be conducted on-site. 

8. Consider an on-site option. To provide the option of on-site fitting and adjustment, plus a high degree of security and seal integrity comparable with that of crimped fittings, there are now some highly effective safety clamps on the market in aluminium, brass and stainless steel.  These clamps comprise two interlocking hemispherical shells bolted around the hose end using a locking collar, with an inner safety rim that fits over the hose shank collar.  If the bolts are correctly tightened the fitting cannot be pulled from the hose, providing an effective, leak-free seal for hose pressures up to 25 bar. 

9. Operate a consistent maintenance programme.  Having established the right hose assembly for the application and carried out the correct installation, complete hose assemblies should be checked regularly for damage and wear.  The need to protect productivity and profitability is great in all applications but the issue can be critical in industries such as food, beverage, chemical or pharmaceutical processing, where cracked, perished and leaking hoses may lead to contamination, waste and plant downtime.

10. Consider a hose testing service.  Some suppliers now offer a cost-effective hose testing service, with hose assemblies being visually inspected, pressure tested and checked internally with a fibre-optic camera.  Once tests are completed the customer is advised of any failed hoses before they can be re-fitted to the plant.  A testing programme may also offer further benefits in that test results can be logged in an online asset register to build a valuable data resource.  This can assist with long term plant maintenance programmes and play an important role in helping users to cut hose replacement or repair costs. 

Topics: Best Practice, Hose Technology, Fluid Power, Transfer & Control

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