Possible cause of steam trap failure (2)

Improper drainage

In the diagram, one can see if the condensate discharge too high, or the drip leg to narrow , it will cause condensate cannot enter to steam trap smoothly

Possible cause of steam trap failure (1)

The trap outlet piping is submerged, the inlet pressure drops and dirty water or foreign object get sucked into the trap causing failures.

Steam trap doesn't have the function of check valve.
Below diagram shown how to do the correction:

Potential cause of Mechanical Seal failure

As study shown, mechanical failures contribute 24% of all mechanical seal failures.

Here I listed that 4 area that you need to pay attention to.

1) Alignment of pump

Shaft misalignment, coupling imbalance, and impeller imbalance can all contribute to mechanical seal failures.

2) Piping strain the pump

In addition, after the pump is installed, if you have misaligned pipes bolted to it, you will impart a lot of strain on the pump.

3) Pump foundation

You also need to avoid a bad base: Is the base secure? Is it grouted properly? Do you have a soft foot? Is it bolted correctly?

4) The right bearings

And last, check the bearings. If the tolerance of the bearings wears thin, the shafts will move and cause vibrations in the pump.

The belt's science: Select Correctly Install Effectively Never Compromise Efficiency.

Effective, correct installation will ensure your belt drive lasts longer and works more efficiently throughout its service life.

One of the most common mistakes – made in 70% of installations – is to fit a new belt to a worn pulley.

 This wastes energy and not only compromises the efficiency but also the lifespan of the new belt.

In fact, the kind of lifespan you can expect from a new belt decreases drastically depending on the pulley it’s fitted to:

• New belt / new pulley – approx.. 25,000 hours’ life
• New belt / worn pulley – approx.. 12,000 hours’ life
• New belt / severely worn pulley – less than 1,000 hours’ life

Often, the pulley won’t be replaced because it’s considered too costly to do so. But if a pulley with worn grooves is replaced at the same time as the new belt is installed, it will quickly pay for itself by restoring optimum drive efficiency, by lengthening the life of the belt, by reducing maintenance requirements and by minimising downtime.

Useful tips for Maximising Bearing Service Life

Every bearing has a pre-calculated service life, however research has shown that two thirds fall short of their potential lifecycle.
Here i listed down 10 points plan to help you to get the most from their bearings.

1. Select the correct bearing

2. Fix and align

16%  of premature failures are as a result of incorrect fittings. Adhere to correct fitting practices and you can help to extend the bearing’s service life and reduce costs over time.

3. Correct sealing arrangement

4. Maintain lubrication

36 % of premature bearing failures occur as a result of incorrect specification and the inadequate application of lubricant. Getting the right lubricant, in the right quantity and at the correct interval levels is therefore essential. 

5.  Monitor bearing condition 

6. Plan for replacement 

No matter how much you care for your bearings, they will need to be replaced at some point or another and condition monitoring can help you to plan for that replacement.

Pump maintenance - check the shaft run-out

Shafts get bent. The spinning impeller has unequal loading on in causing the shaft to deflect away from the volute throat. Constant deflection causes weakness and can lead to a permanent offset of the shaft leading to shaft run out. 

Shaft run out is bad for seals. It causes them to flex twice on every revolution of the shaft. At high enough speeds this can cause a vibration in the seal which allows the seal faces to OPEN. BANG failed seal.

So, it is important to  check the shaft of your pump for any damaging shaft deflections by using the Dial Test Indicator (DTI).

Single stage pumps should be checked near the seal running position but multi stage pumps should be checked at suitable intervals along the shaft as well as at the seal running position.

The run out should not exceed 0.002 inches or 0.05 millimetres.

Quick way to determine pump Head and Capacity by increase impeller diameter

Here I would like to share with you all the quick way to determine pump Head and Capacity by increase impeller diameter.

Normally centrifugal pump will have 10~20 % allowance if the impeller size increase to max.

For example : original impeller diameter D1 = 301mm  D2 = 320mm and pump head  H1 = 33

The new pump head H2 will be (D2/D1)^2 * H1

and for the pump capacity, as well you can do calculate in this formulae

Quick way to determine Q2 will be (H2/H1)*Q1

Safety valve spring length

Why in B.S code stated that the length of the spring should be less than 4 X OD of the spring?

Answer: 
If the height of compression spring is more than 4 times the spring OD, the spring could buckle sideways and rub on the housing wall.

Conventional gland packing Vs. mechanical seals

Thinking of making the switch from conventional packing to mechanical seals?
Before we make the decision, let’s read on for a basic understanding of mechanical seals, and how they differ from packing.

WHY DO PUMPS NEED TO BE SEALED? 
Let's go back to some pumping basics and review how a centrifugal pump operates. Fluid enters a centrifugal pump through the suction nozzle at the center of a rotating impeller. As the impeller rotates, its vanes fill with fluid, then force it out to the pump casing where it exits the pump through the discharge nozzle.
Unfortunately, the discharge pressure will force fluid back behind the impeller, where it attempts to exit by way of the rotating drive shaft. Attempts have been made by pump manufacturers to minimize this leakage through design, but the leakage won't be stopped entirely.

Some form of sealing method must be put in place to minimize the leakage.

USING PACKING AS A SEAL Packing materials were originally the sealing method of choice, using soft, flexible materials. It's a very popular method of sealing pumps because of its low upfront cost, easy installation, and readily available materials.

USING MECHANICAL SEALS The biggest benefit of using mechanical seals is the drastic reduction in leakage. That reduction in leakage also has an effect on a number of other things as well. Things like a safer work environment without a wet floor, fewer bearing failures caused by leaking fluid, no excessive wear on the shaft sleeve damage from packing.
However, Mechanical seals are complicated pieces of equipment, with a wide variety of materials and configurations to choose from, be sure that what you invest in is exactly what you need for your application.

Thumb of rules: If the medium use is water, gland packing will be the choice because of it convenience, but when come to flammable or oil base medium the mechanical shall be the top selection.

How to ensure quality tightening of flange's bolt

1) Calculate the minimum required bolt loads (refer to ASME Sec. VIII)

2) Calculate the tightening torque

3) Ensure bolt length are 2~3 thread out of nut

4) Slightly hand tighten the flange and measure the gap (to ensure even gap and keep the reading ad initial before gasket compress)

5) Tighten the bolts with applied torque and diagonal pattern

Canned pump assembly tips

The picture shows some of the tips in canned pump assembly :

1) do not forget the lock washer
2) locknut' plate do not forget to bend to lock it
3)and lastly the nut on the front plate make sure sucure fasten

Canned pump carbon bearing setting

In replacing carbon bearing(B012),fix the  carbon bearing into bearing housing after putting the sheet(S26) into a cutout on the outer side of the carbon bearing.

 Tighten the setscrew(231) until it contacts the sheet. At this time, it is recommended that carbon bearings rotate to the right-hand and left-hand slightly.

 If the setscrew tightening too much that may cause carbon bearing crack & tightening too loose that may cause carbon bearing turning when star up.