How to Lift Tanks.com

MTS Tank Technologies
Single Stroke Jacks Tank Turtles Unified Oil Volume Distribution System MTS Pile Driver Foundation Repairs Foundation Designs Tank Moving 
Tank Lifting Preparation Under Floor Grouting External floating roof lifting:Rocket launchers
Tank Construction
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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.

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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.

 

 Each Tank Turtle™ is driven, so traction is never a problem, Turtles have nearly 8” of heavy duty suspension travel allowing the tank to be maneuvered over rough terrain without any problem. The system is designed to work in conjunction with MTS singe Stroke jacks and allow MTS incredible versatility in the tank moving options they can offer.

Return to Top                                                   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.

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                                                                      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.

 
With this type of foundation tank settlement should be expected, sometimes severe enough to require immediate repair before the tank can be put back in service. However with the MTS tank lifting system, the tank can be raised and the foundation built up on top of the consolidated material and put in service for about one fifth the cost of installing piles.


 
It is not a bad idea to include lifting and repair of the foundation after hydro test or after a few years of service of the tank as part of the foundation design plan. It is actually more cost effective than pilling the entire area. There is a tank terminal company that does exactly this right now and has saved over 25 million dollars in the construction of new tanks over a period of 3 years at their Louisiana terminal location.

 
They have required MTS to lift only 3 of the 20 newly constructed tanks after the hydro test, the rest are performing adequately although settlement is observed. When this settlement is bad enough in a few years or so, they will give MTS a call to come lift the tank and affect the necessary repairs. This is still far more cost effective than piles, and this is not an irresponsible plan because most tanks are built without pile foundations, and so this is no different than the way all the other tanks were done in the past, and most still are today.

 
Piles are necessary when the client has no time to do a long hydro-test and let consolidation occur over months of holding the water, during this time some tanks will settle and sink badly and require us to come in and lift the tank to remediate the foundation, but most will settle acceptably enough to go directly into service. A small gamble yes, but MTS and their tank lifting system makes it a very cost effective option; it still costs less to have MTS come in, lift the tank and repair the foundation than it does to install the piles; a lot less!

 

 MTS has a pile driving system that can easily install piles around the perimeter underneath the concrete foundation with the tank in place. MTS has driven the piles all the way down to the hard pan and has simply installed resistance pile this way. Resistance piles around the perimeter are a good choice because it allows for pad settlement while at the same time controlling differential edge settlement and planer tilt without over supporting the shell. If the shell is over supported with piles then the floor may settle faster then the shell, causing problems.

Upper Right: pile being pushed around perimeter of existing tank.
Upper Right Mouseover: section of pile being added and coupler welded.                   
   
   Left: MTS  designed pile cap; when affixed to steel reinforced ring wall, all piles must move in unison. This type of system is used when differential settlment needs to be eliminated  around the shell, when blanketting the pad area with piles is prohibitive.
 These piles are not driven all the way to hard pan, but are driven to a calcualated predetermined resistance. The MTS pile driver allows for accurate measurement of this resistance to assure even settlment around perimeter, while also allowing the shell to match the settlement of the tank floor pad area.

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It is often necessary to lift tanks so that they can be moved by one means or another and MTS jacking systems are ideal for this. MTS moves tanks as a matter of routine, but are also willing to assist other tank moving companies using our jacking systems and Tank Turtles™.

Tank Turtles Moving Tank Over Bridge To Cross Pipe Lines           Tank Turtles Used During Hurricane Recovery
Mouseover: MTS Jacking system used to assist one of our           Mouseover: MTS Jacking System used to load 4 tanks
competitors move a tank.                                                        on to trailers for 20 mile trip across Saskatchewan    
                                                                                             Prairie
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                                                                                     Tank Lifting Preparation       

 

Before a tank can be lifted it needs to be properly supported to assure that no damage occurs to the internal structures of the tank. The floor and roof structures need to be supported, otherwise the floor will sag, the roof will sag, and with it all the rafters will sag.

 Geometrically speaking when a tank has a cone roof, the rafters are longer than the actual foot run to the center of the tank; for example, on a 100’ diameter tank it is 50’ to the center of the tank, but if the tank has a slight cone up of only 2’ then the rafter length would be about a half inch more than that. So when the roof sags down this put tremendous strain on the rafter system and has a tendency to rotate the columns and cause them to begin racking.

  A half inch does not sound like much but imagine taking a 50’ I-beam and compressing it end from end until you moved those two ends that ½” closure to each other. As you can easily imagine, it would take tremendous force to do this, and the I-beam would either bow or bend like a snake to make up the distance change. Now imagine the strain this puts on the rafter clips at the shell connection, so you can see how improperly supporting the tank floor will cause detrimental wear and tear on your tanks.


                                                                  
                                      MTS has been high-lifting tanks longer than anyone else in the industry; they were the first and are the best.
                                                                                                                                                                                                                                                                                                          MTS supports the floor with a spoke like system of cables that goes from the top of the shell to the floor. MTS uses a cable size that limits the amount of possible load that can be conducted to the top of the shell at any one point. Then a five to one safety factor is calculated so that the small sized cable only has to support one fifth of the cable rating. This assures that the floor is evenly supported and no sag is allowed to occur. When the tank is lifted, the tank never even knows it has left the ground.  

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                                                                      Under Floor Grouting                 


MTS is set up to perform under floor grouting in those situations where the floor is settled and the floor profile needs to be restored. MTS can pump grout under the floor to re-profile the floor without the need to lift the tank. However if large quantities of grout is required it can be cost prohibitive. Concrete supply companies do not like to deliver large quantities of grout because it requires too large of a commitment for their cement trucks to deliver the grout.

  Grout is usually about a third the cost of regular concrete and so if they tie too many trucks up delivering the lower priced grout they can’t use them to deliver the much higher priced concrete to other customers. The net result of all this is they will limit their delivery of grout to less than eighty yards a day, or charge as much for the grout as they do for concrete; this makes grouting cost or time prohibitive on larger amounts.

 Grout pprojects are usually viable if the projected amount of grout required is less than 1000 yards. Most tanks under 140’ diameter with a reasonable amount of floor settlement can be cured with less than 1000 yards of grout. So in those cases this is not an unreasonable option to consider


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                                                             External Floating Roof Lifting: Rocket launchers                            

 

MTS has specially designed Floating roof lifting jacks assemblies called Rocket Launchers.  This system is used to raise floating roofs to allow more clearance to allow better access to the underside of the roof.

 

 Rocket Launcher used to lift floating roof to facilitate instalation of 6000 yards of material to rebuld floor pad profile and floor replacement on 375' diameter tank.


MTS has lifted and cribbed roofs for floor replacement to allow clearance for Skid Steer equipment to assist in the placing of floor sheet, for better access to clean the tanks, and to lift floating roofs that have collapsed due to corroded legs or the weight of flooded pontoons and then safely crib it up for safe access to clean and make the necessary repairs.


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                                                                              Tank Construction            

MTS has experience in tank construction using jacks to lift the tank as each shell course is installed. MTS are no longer in the tank construction business however MTS is willing to assist any tank builders who are interested in building tanks this way by offering technical expertise and assistance while jacking the tank for them as the tank is being constructed.

 The MTS Hi-Lift jacks were originally built and used for building tanks in this fashion.

 For more info contact dave@mixbros.com  






Roof and top course is built first, then lifted to              
fit next course      
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