Stresses in Piping systems

Hi all,

This is one of my favourite topics, since I had a large number of systems piping failures related to stress, mostly external.

One of the flange connections of the fire main systems on board a ship, couple of bolts used to break at the head frequently; more often if the ship had done some high-speed manoeuvres.  Initially, we used to change the bolt and live with it, but a nagging doubt came into our minds and we did a root cause analysis. What we finally found was that, the last pipe that fitted into the system was a little oversized and had been forced into its slot using a chain pulley, thus leading to a stressed piping section. Whenever high vibrations occurred, the stress used to increase, thus resulting in the flange securing bolts at one end shearing.

I came across a nice article on the topic. Please read and be enlightened on the topic.




Condition Based Maintenance – Monitoring Tools


I keep getting updates on new products used in the maintenance field through various online subscriptions.

Here is a link that shows the us of Ultrasound devices in the condition based maintenance strategy. I am not trying to sell the product, but am just trying to propagate the techniques involved. Please connect to the link given below and learn more.


Case Study on Advantages of Proper alignment of Rotating Machinery Assemblies


Good, within tolerance, mechanical alignment between the driving motor and driven components is one of the basic health requirements.

I came across an excellent case study for which the link is given below.

Proper alignment helps one plant keep on pumping.

Please go through and be enlightened.


Combine vibration monitoring and ultrasound for more cost-effective predictive maintenance

Hi all,

predictive maintenance is one area that needs no introduction. Combination of techniques and tools available currently makes this a very competitive process. With this process, we can determine when to do any maintenance. Yes, preventive maintenance processes also will be followed, but instead of doing them mechanically as per a time schedule, it gets done when it is required to be done.

In most cases, the buffer time provided for time based preventive maintenance schedules is too much and we end up over-maintaining the equipment causing the following:

  • Doing maintenance on fully functional, healthy and operational equipment
  • Replacing the mandatory spares and consumables every time we do maintenance
  • Creating a condition where the equipment could fail due to man-made mistakes during assembly of equipment, post-maintenance.

I came across a wonderful article covering predictive maintenance using a combination of techniques and tools. The link is given below.

Predictive Maintenance: Combine vibration monitoring and ultrasound for more cost-effective predictive maintenance.

Please take some time to look up the link, read and be enlightened.


Good vibrations – Bad vibrations – Back to Balance

Hi all,

Years spent operating and maintaining marine gas turbines on ships have left me very sensitive to the issue of bad vibrations. The salt-laden humid sea air entering the compressor section of the marine gas turbines leave salt deposits on the blades. If not attended to regularly, the deposits will tend to foul the air flow and lead to something known as “Compressor surge”, that leads to air flow becoming disturbed and oscillating from and to the turbine end. This surge can cause catastrophic failure of the turbine as a whole, due to the sporadic and violent directional changes in axial loading on the bearings.

Taking another type of equipment this time; High speed exhaust blowers connected to automobile paintshops tend to collect paint sludge and vapour condensation on the blades over time. This causes imbalance to the rotor and leads to bad vibrations. If not corrected in time, premature bearing failure and catastrophic damage to the equipment can occur.

I came about a well written article in the recent edition of Plant Services e magazine. The link to the article is given below.

Tactics and Practices: Back to balance.

Please read and be enlightened.

Condition Based Maintenance or Predictive Maintenance practices for critical equipment can help the maintenance personnel to lesser job stress and higher labour productivity.