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Showing posts with label skidding. Show all posts
Showing posts with label skidding. Show all posts

Friday, January 10, 2014

Horizontal Shifting- The unconventional way

In my last blog posts i have been discovering through the history about the ways people tackled the challenge of shifting heavy loads. I will explore the heavy lifting in my upcoming posts. For now i will stick to the horizontal shifting.

Why unconventional means of shifting if you have modular transporters (Modular Trailer or SPMT)?
There are situations where these conventional methods cannot meet the challenges. In cases where there are space constraints. In cases where site situation is such that the use of conventional techniques cost seems too high with respect to the project cost.

I will start with a seemingly funny (mind it, its genius stuff) but effective example shown below.
This photograph is reported from the Indian state of Kerala where a coconut tree was shifted to clear the area for construction work.
Instead of chopping the tree off these ingenious guys decided to shift the tree instead. Commercially i can not compare the cost between chopping off the tree with this method but i can surely say that the life of the tree was definitely saved, which is priceless.
In heavylift lingo, this method is known as "Skidding".

Skidding can be done either pulling or pushing. In heavy lifts we use either 
  1. Winches or Strand Jacks
  2. Push Pull Cylinders (Compensating Technique)
In both the cases skid tracks, friction reducing materials like Teflon or PFC and Power Packs are common. Elevation cylinders for negating the effects of unevenness of the underlying surface is also used on case to case basis.
Below is an example of use of Strand Jacks for Skidding.
Installation of strand jacks
Getting in the strands


Skidding is in process
Load out of 14500T Jacket. South China Sea, 130km offshore Sabah in East Malaysia. Executed by SARENS.
I will explore other Skidding techniques and the its importance in my next blog.

Saturday, December 14, 2013

The heaviest monolith quarried and transported

We often are awed by the heavy lift marvel jobs which happen today. Not to mention, the heavy lift contractors themselves try to gain as much publicity when they do the "heaviest" or the "biggest" lifts or transports.
I used to think that todays equipment and engineering has made us far better in heavy lifts than what we were say 100 years back. I was wrong...point blank.
I recently came across an event in the history which happened in the year 1768. This was the shifting of a 1250T monolith for a distance of 6km. Wikipedia states that its still holds the record for the heaviest quarried and moved monolith.
I am talking about the Thunder Stone at St Petersberg.
The shifting equipment was designed and the project was ingeniously engineered and executed by Marinos Carburis, the first Greek to hold a diploma in Engineering.
Since, the stone had to be shifted from marshy terrain, they waited till winter so that the soil is frozen and hard. It was then transported from the quarry area to the ship and then to the city.
"He developed a metallic sledge that slid over bronze spheres about 13.5 cm (6 inches) in diameter, over a track. The process worked in a way similar to the later invention of ball bearings"- Info Source http://en.wikipedia.org/wiki/Bronze_Horseman#Thunder_Stone

I was humbled. Designing and use of balls for sliding or skidding before even invention of ball bearings is out of the world. To surprise you more...this technique of shifting is used even today by heavy lift contractors!