Flat Jacking

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Flat Jacking Systems

Hydra-Capsule low-height flat jacks range from 8 to 1,380 tonne capacity. These low-height jacks are capable of exerting extremely high thrust forces. They are normally used within the civil and construction industries for a multitude of applications, such as, lifting heavy structures, stressing operations, transferring existing loads to temporary or permanent supports and permanently pre-loading buildings, structures, and bridge bearings to seismic isolators.

Due to their design, they are not only light in weight but require a minimal installation gap or just a few centimetres, when selecting a flat jack, the ideal working range should be about 75% of the jack's capacity

Permanent Units

Where a permanent force/load is require to a structure, flat jacks are installed in-situ and inflated using a high pressure injection system, epoxy resin or cementitious grout can be injected, but grout filled units are normally recommended in order to meet the current day environmental and fire regulations.

This application is primarily implemented whilst carrying out works for pre-loading of structural steelwork or part of structural alterations, pre-stressing, underpinning and structural and bridge bearing pre-loading.

It’s essential that the mixing and grouting operation is carried out quickly and efficiently and we would therefore strongly recommend that our experienced Engineers carry out such operations as mistakes can prove to be expensive.

Hydra-Capsule provide a full design, in-house manufacturing and flat jacking installation service offered throughout the UK and Internationally. Bespoke flat jacks can be manufactured for special applications.

Advantages:

Forces from 8 tonnes upto over 1,380 tonnes (offering the largest selection worldwide)

Measuring and control of induced thrust forces and loads

Load transfer and steelwork deflection device

Balance force loading on double-stack flat jack arrangement

Access restraints for wedging and grouting of gap

Low height jack as small as 35mm gap

Ideal for underpinning and pre-stressing

Can be used for temporary (hydraulic oil / water) and permanent (grout and resin) applications

3 different types and pipe arrangements (below image)

3 different type and pipe arrangements fj

Circluar from 8 to 1,380 tonnes Capacity

JACK CODE	CAPACITY (tons)	CLOSED HEIGHT	OUTSIDE DIAMETER	THRUST DIAMETER	MAXIMUM STROKE	MAXIMUM PRESSURE	FLUID LITRES	WEIGHT (KGS)
FJ 12	80	32	120	75	25	150 bar	0.3	4
FJ 15	150	32	150	105	25	150 bar	0.5	8
FJ 17	200	32	170	125	25	150 bar	0.8	9
FJ 19	250	32	190	145	25	150 bar	1.1	10
FJ 22	400	32	220	175	25	150 bar	1.2	16
FJ 25	500	32	250	205	25	150 bar	1.3	19
FJ 27	600	32	270	225	25	150 bar	1.6	20
FJ 30	800	32	300	255	25	150 bar	1.9	23
FJ 35	1000	35	350	305	25	150 bar	2.6	26
FJ 38	1300	35	380	335	25	150 bar	3.1	27
FJ 42	1600	35	420	375	25	150 bar	3.6	29
FJ 45	1800	35	450	405	25	150 bar	4.1	30
FJ 48	2100	35	480	435	25	150 bar	4.7	32
FJ 52	2650	35	520	475	25	150 bar	5.7	36
FJ 56	3000	35	560	515	25	150 bar	6.2	38
FJ 60	3450	35	600	555	25	150 bar	7.4	43
FJ 67	4800	35	675	625	25	150 bar	9.6	59
FJ 69	4900	35	690	645	25	150 bar	10.5	67
FJ 75	6000	35	750	700	30	150 bar	12.4	90
FJ 75B	6000	45	750	700	50	150 bar	19.8	95
FJ 87	7640	35	870	825	30	150 bar	16.8	111
FJ 92	8680	35	920	875	30	150 bar	18.7	126
FJ 102	10300	40	1020	940	32	150 bar	24.4	175
FJ 108	13800	40	1080	1030	32	150 bar	28.1	195

Applications for flat jacking

Preloading of Steelwork and Load transfer

Excavation Struts, propping and shoring Jacking & Preloading

Lifting and Weighing

Settlement and Structural Jacking

Hydraulic to Permanent Transfusion

Bridge Deck Lifting and Bridge Bearing Preloading

Temporary Flat Jacks

When Flat jacks are required for a temporary duration and then subsequently removed, this operation is usually carried out with water or hydraulic oil fluid.

The benefits of temporary flat jacks:

Use as a load cell (pre-inflates), connected with a pressure gauge or digital transducer read-out

Continuous load monitoring and adjustment

Multiple flat-jacks circuits

Ability to transfuse from a temporary to a permanent application (epoxy resin or cementitious grout)

Transfusion Units

Single Flat Jack

Transfusion flat jacks are specially designed in-house, and manufactured by Hydra Capsule. These flat jacks have the ability to transfuse grout whilst under load, from a temporary to a permanent load. The design of the flat jacks allows for a balanced load and movement displacement throughout the grout transfusion operation.

Double-stack Flat Jacks

The same can be achieved as the double-stack flat jack arrangement. However, the transfusion method is inflating one flat jack, whilst the other flat jack is deflated and maintaining a constant balance load between both flat jacks.

Rectangle Flat Jack Systems

Hydra-Capsule Limited provides specialist rectangle flat jack systems for structural testing, controlled load application, masonry stress analysis and precision correction works.

Our flat jack solutions are used across heritage structures, bridge works, façade retention schemes and structural modification projects where controlled, uniform pressure must be applied within restricted spaces.

Designed for accuracy, reliability and minimal intrusion, rectangle flat jacks allow force to be introduced directly into structural elements without large-scale dismantling or disruption.

Rectangle flat jacks are thin, high-pressure hydraulic steel envelopes inserted into pre-cut slots within masonry, concrete or structural interfaces.

When pressurised, the flat jack expands vertically, applying a controlled and evenly distributed force to the surrounding structure.

Their slim profile makes them ideal for:

Masonry stress testing

Structural crack correction

Controlled load transfer

Bearing pressure verification/pre-loading

Compensation grouting interfaces

Applications

Structural Testing & Stress Measurement

Flat jacks are widely used for in-situ stress measurement within masonry and historic structures. By relieving and reapplying compressive stress, engineers can determine:

Existing compressive stress levels

Structural capacity

Load distribution behaviour

Residual stress conditions

This method is particularly valuable in refurbishment and conservation projects.

Square from 40 to 360 tonnes Capacity

JACK CODE	CAPACITY (KnS)	CLOSED HEIGHT	OUTSIDE DIAMETER	THRUST DIAMETER	MAXIMUM STROKE	MAXIMUM PRESSURE	FLUID LITRES	WEIGHT (KGS)
SFJ20-20	400	35	200X200	155X155	25	140 bar	0.5	4
SFJ25-25	600	35	250X250	205X205	25	140 bar	0.5	8
SFJ30-30	900	35	300X300	255X255	25	140 bar	0.8	9
SFJ35-35	1600	35	400X400	355X355	25	140 bar	1.1	10
SFJ40-40	1600	35	400X400	355X355	25	140 bar	1.2	16
SFJ45-45	2000	35	450X450	405X405	25	140 bar	1.3	19
SFJ50-50	2500	35	500X500	445X445	25	140 bar	1.6	20
SFJ60-60	3600	35	600X600	555X555	25	140 bar	2.6	26

Rectangular from 50 to 500 tonnes Capacity

JACK CODE	CAPACITY (KnS)	CLOSED HEIGHT	OUTSIDE DIAMETER	THRUST DIAMETER	MAXIMUM STROKE	MAXIMUM PRESSURE	FLUID LITRES	WEIGHT (KGS)
RFJ20-25	500	35	200X250	155X205	25	140 bar	0.3	4
RFJ25-30	750	35	250X300	205X255	25	140 bar	0.5	8
RFJ30-35	1050	35	300X350	255X305	25	140 bar	0.8	9
RFJ33-38	1250	35	330X380	285X335	25	140 bar	1.1	10
RFJ38-43	1600	35	380X430	335X385	25	140 bar	1.2	16
RFJ43-48	2050	35	430X480	385X435	25	140 bar	1.3	19
RFJ48-53	2550	35	480X530	435X485	25	140 bar	1.6	20
RFJ53-58	3050	35	530X580	485X535	25	140 bar	2.6	26
RFJ58-63	3650	35	580X630	535X585	25	140 bar	2.9	31
RFJ63-68	4250	35	630X680	585X635	25	140 bar	3.3	36
RFJ68-73	5000	35	680X730	635X685	25	140 bar	3.6	41

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Flat Jacking

Flat Jacking Systems