HOW TO LIFT TANKS 504-458-5675
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Single Stroke Jacks
The Single Stroke moniker refers to the ability for the jacks to lift the tank to the full desired lift height in one stroke without being reset. The Hi-Lift jacks can stroke over ten feet in one smooth stroke, without needing to be reset, and since most high lifting of tanks is ten feet or less and the jacks can lift a tank to that height in one single stroke.
Single Stroke Hi-Lift jacks were specially developed for the purpose of lifting large AST tanks. They are designed so that in most cases no Lifting Lugs are needed and no welding to the tank shell is required. They lift directly under the shell where the bulk of the weight of the tank is, and this is also the strongest part of the tank. MTS has single Stroke Hi-Lift jacks as well as Single Stroke Medium Lift jacks and Low Lift jacks.
The single stroke medium lift jacks are shorter, designed for situations where the tank does not need to be lifted as high. The medium lift jacks can lift a tank to nearly four feet in one stroke, and are often used to correct edge settlement around the perimeter of the tank or in conjunction with our Tank Turtle? tank moving system. The low lift jacks are just a shorter version used for correcting edge settlement.
Tank Turtles?
The MTS Tank Turtle moving system is a modified walking beam system that allows tanks to be moved easily in even the most adverse conditions. It is capable of traversing large distances, but it travels at about walking speed or less, so this is a limiting factor. Size however is not; any size tank no matter how large can easily be moved with this system. It can climb a grade, cover soft ground without fear of getting stuck, maneuver in very tight spaces, and rotate a tank in place.
If the tank can fit there, the Turtles can put it there.
Unified Oil Volume Distribution System
The key component that allows MTS to lift a tank with long single stroke Hi-Lift jacks is their specially developed unified oil volume distribution system called a Unifier. This machine delivers an equal volume of oil to each jack circuit. This is not the same as equal pressure; all hydraulic pumps deliver equal pressure to each circuit connected to the pump unless acted on by an outside force.
Hydraulic oil, like anything else, will always follow the path of least resistance, so an equal pressure system will deliver the bulk of the volume of oil to through the largest lines and the shortest lines first. It will go to the device that is the easiest to move, whether it is a hydraulic jack cylinder or a hydraulic drive motor. What ever move easiest will be where all the oil goes. That is why unified oil volume distribution to each circuit is required.
If each hydraulic jack circuit is not supplied with an equal volume of oil the jacks with the shortest lines and the lightest load will lift first, and the jacks with the longest lines and the heaviest load will lift last. In short this means that the tank will lift crooked, and the higher the tank is lifted, the more crooked it gets.
If a unifier is not used each jack is essentially on one single supply manifold, and in that configuration even a slight breeze will cause the tank to lean. This is because the oil is shared between jacks, and so the oil will transfer between jacks travelling along the path of least resistance. The unifier individualizes each jack circuit so the oil cannot transfer between jacks, this means that the jacks stay where they are at, and resist any wind loading or weight differential of tank.
By using the unifier, all these problems are eliminated, each jack circuit is delivered the exact same volume of oil regardless of line length resistances, weight differentials or wind loading, each jack will move at the same speed as the others. If two cubic inches is delivered to the jacks close to the unifier, then two cubic inches of oil is delivered to the jacks farthest from the unifier. Likewise, if two cubic inches of oil is delivered to the jack with the least weight on it, then two cubic inches of oil is delivered to the jack with the most weight on it simultaneously. This assures a perfect perpendicular lift, keeping the tank stress free, straight and level all the way up, and all the way back down again.
MTS developed a specialized unified oil deliver system specifically designed for the lifting of large tanks with long single stroke hydraulic jacks. There are other unified oil delivery systems available for other applications, but they have limitations in how much uninterrupted unified oil volume they can deliver, which means they are not adequate for supplying long single stroke jacks that can lift a tank 10 feet high. The MTS unifiers are designed specifically for lifting tanks, and are exclusive to MTS.
MTS Pile Driver
MTS developed a pile pushing device specifically designed for installing piles around the perimeter of and existing tank. This device is designed to push the pile into the ground hydraulically into the ground, by knowing the amount of oil pressure it takes to drive a pile we can determine how much of a load each pile can support.
This is important because it is not always a good idea to only support the perimeter with piles, as the floor of the tank could continue to sag, causing worse problem. But by engineering a pile system that controls the amount of settlement of the perimeter ring wall, it can be matched to the settlement of the tank floor area.
This allows for increased service life of the tank, so even though it may still be sinking, it settles evenly. The pile cap MTS uses was designed to reduce and even eliminate the planer tilt and differential settlement by connecting them as a unit so they all must settle perpendicularly. This keeps floating roofs working better longer, and keeps tank within API specifications longer. Settlement issues like these are not experienced everywhere, but are a considerable issue in the Gulf States, and especially in Louisiana.
Return to Top Foundation Repairs
The main reason tanks are lifted is to correct edge settlement and or replace or upgrade the existing foundation. MTS provides foundation designs that are specially suited for this type of repair. Taking advantage of the consolidation created by the years of in service tank operation these foundations routinely outperform the original foundation and new foundations.
Installing concrete ring-walls around the perimeter to carry the shell weight, and building up the profile of the pad back to original or raising the entire tank to a higher elevation is routine for MTS.
MTS foundation designs have proven themselves over and over in some of the toughest environments from northern Canada to the deep south where swamp like conditions wreak havoc on tank farms and excessive settlement of AST tanks is a common problem.
Typical Louisianna Tank Settlement Steel Reinforced Concrete Ring-Wall
When building Steel reinforced concrete ring-walls it is not necessary to do a monolithic pour. The ring wall is placed under the shell around the perimeter of the tank, the shell by its sheer size and height act as a large steel beam that spreads the load out evenly on the foundation, so as long as proper rebar overlap is maintained, and ground footing is properly compacted, there is no reason to perform a monolithic pour. MTS uses Fillcrete, a type of flow-able fill, that gives the steel reinforced concrete ring wall an excellent base.
As shown on in the picture (above right) the tank will be lowered onto the individual piers, the jacks removed and forms installed and then this part is poured last.
Return to Top Foundation Designs
MTS has recognized that most tank foundation issues occur around the perimeter of the tank under the tank shell. This is where most of the weight of the tank is and is the part of the foundation most exposed to the elements. Rain water flowing off the roof and down the shell keep this area constantly soaked and eroding, this leads to edge settlement. A gravel footing is often not adequate here as it will over the years be eroded by this process.
Over time, even very well compacted gravel will absorb this water, and this water will soften the ground under the gravel and with each loading and unloading of the tank will cause migration of the mud into the gravel and gravel into the mud. A geo-tech cloth can prevent this migration; however the wet gravel will still soften the ground and create a mud base under the gravel which will be displaced causing the foundation to sink.
A better choice is to use a flow-able fill instead of gravel, this fill made up of sand and cement will form a strong water resistant barrier around the perimeter protecting the load bearing soil from the excessive moisture caused by the roof run off. It is installed by simply lifting and supporting the tank, trenching out around the perimeter under the shell and pouring the fill directly into this trench.
The trench profile is of course somewhat irregular and the flow-able fill conforms and hardens to this profile; this keying-in effect has a tendency to increase the effective bearing area of the foundation beyond the actual dimensions of its foot print, providing greater bearing surface to support the tank foundation.
Some new tanks are now being built on a pile foundation. To support the floor of a tank there needs to be a lot of piles driven and care must be taken to properly cap the piles so that they do not point load the floor and eventually poke through the floor. This is a very expensive operation and can cost more than the value of the tank. In many cases, the most cost effective method is to build a gravel ring-wall and a batcher dirt or sand pad capped with PH neutral sand.
Jesse Quirk
Project Manager / Business Development Representative
Office: 985-764-3300
Cell : 985-709-6792