Principals / Partners


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Principals / Partners

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Den Holders Principals/Partners


Manufacturer for differential pressure flow equipments, special fittings and pipings for oil and gas industries.


Since 1921 ... 

Den Holder

Our products are differential pressure flow elements such as orifice plates and venturi tubes, but also other special piping parts such as length compensators, strainers, sample coolers and spectacle blinds.

Our main goal is to deliver products of the highest quality and maintain a long-term relationship with all our clients.


Product List:


insu 1


Flange Insulation Sets which include gaskets (type F, E or D), sleeves and washers. The most common style of gaskets is Type ‘F”, where the gasket is designed to fit in between the Boltholes, Type ‘E’ which is designed with a full-face gasket or Type ‘D’ where the gasket is Ring Type Joint.

The Flange Insulation is required to avoid leakages due to corrosion. Stray electric currents in the piping system can be controlled and electrolytic corrosion eliminated.

Each set will be supplied separately packed and labelled with the flange tagnumber, line size, rating and type. Besides standard sets we manufacture to any required specification.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Flange Insulation Gasket Kits


spiral wound gaskets 3


Spiral Wound Gasket are semi-metallic gaskets designed for high pressure and temperature applications. The gaskets can seal fluid pressures up to 250 bar and temperature range of 200°C to in excess of 450°C. A variety of forms of the gasket is available and these can be manufactured in a variety of materials or sizes to suit requirements.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Spiral Wound Gaskets


junior 1


Junior Type Orifice Fitting is a single chamber orifice fitting used with an interchangeable orifice plate and removable sealing O-rings. It is designed for simple and economical checking and replacement of an orifice plate in measurement installations. The few parts of the fitting are: the body, the sealing bar, the orifice plate, the clamping bar with its sets of bolts, the drainplug and the tapping plugs.

The fitting may be installed in any position on either horizontal or vertical pipelines. If the orifice plate is lifted through the top of the fitting there is no spillage of liquid service. Before changing plate, the pressure in the line or meter tube must be relieved.

With this Junior Type Orifice Fitting, checking and replacing the orifice plate has become a fast, one-man job that only requires a few simple actions.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Junior Type Orifice Fittings




Orifice plates can be designed and calculated in accordance with any required standard. Den Holder standard plates are in stainless steel 316L, with RF gasket surface and with material certificates 3.1B. Of course, all other materials, including material certificates, are possible, as well as other designs and standards, such as DIN or JIS, RTJ oval or octagonal.

Den Holder stamps the measured orifice diameter in the tagplate in order to use the exact dimensions in the flow computer. Strength calculations can be provided to check the thickness against pressure loss over the plate.

Since base materials are in stock for the most common sizes, prices can be kept low and delivery times are short. Rush deliveries can even be made the same day.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Orifice Plates




We manufacture thermowells in each required materials and according every required standard drawing. This means the thermowells can be supplied in any required length with threaded ends, socket weld ends or flanged ends, in which case the welds are made by qualified welders and supported by welder qualification documents. Most common steels and stainless steels are on stock in order to make fast deliveries possible.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Thermowells




Den Holder Compensators (Expansion Joints) are designed, manufactured and tested to be completely safe compensators for pipe-works where quick mounting in and out of various components is required. The length differences that occur because of installing different types of components can easily be accommodated.

The costs of ownership are low, since no more changing of spoolpieces is required and the number of studbolts and nuts that need to be loosened and tightened is reduced by 50%. Unbalanced compensators can slide in and out in a pressureless condition. This can usually be done by hand, but for larger sizes hydraulic or pneumatic cylinders can be mounted on the outside of the compensators. Balanced compensators have the advantage of being completely free of reaction forces. This means that these compensators are completely balanced and will cause no forces in any way when the line is under pressure. Balanced compensators will even compensate forces in the adjoining line pipe which are normally produced by variations in temperature or pressure.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Compensators




Den Holder is a manufacturer of several types of strainers, screens and sieves which are designed in accordance with our clients’ requirements or any international standard. Strainers can be manufactured from pipe, fittings, plate or castings.

Standard designs are T- and Y-type strainers, bucket-type strainers and conical strainers. Other designs can be engineered by us and checked for strength and open area ratio to achieve the lowest possible pressure loss. All strainers are manufactured to the highest standards of accuracy so as to be perfect safeguards with minimum pressure loss.

Design, manufacturing and testing are covered by our ISO 9001 Quality System and all required documentation such as WPS/PQR and NDE reports can be included.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Strainers


orifice flanges and meterruns


Orifice flanges are manufactured as standard according to ASME B16.36, which means NPT flange tappings complete with plugs and jackscrews. In the case of an orifice assembly this can be completed with orifice plate, studbolts, nuts and gaskets. The flanges can be optionally executed with other possible process connections, such as SW, BW, plain-end or flanged welding nipples. This can be completed with valves, condensate pots and differential pressure transmitters.

Orifice Meterruns are fabricated in accordance with ISO 5167 requirements and several construction codes such as ASME B31.3 or Stoomwezen Rules for Pressure Vessels. Apart from flange tappings, the orifice flanges in can also be executed with corner, radius or pipe tappings. The flanges can be optionally supplied with dowel pins to ensure correct positioning of pipework up- and downstream of the orifice plate. Both orifice flanges and meterruns can be supplied in any required material complete with material certificates 3.1B or 3.2.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Orifice Flanges and Meterruns




Long Radius Flow Nozzles and ISA 1932 Flow Nozzles are manufactured from forged bar and can be welded in the line or placed between two (orifice) flanges. In that case the Nozzles are supplied with a spacer ring and gaskets. It is also possible to deliver the Flow Nozzle as a pipe spool with flanged or buttweld ends.

Venturi Nozzles are designed according to ISO 5167 or DIN 1952. The Venturi Nozzles are manufactured from forged bar for sizes up to 12” to guarantee maximum roundness. A combination of forged bar and rolled plate is used for larger sizes. All welds are always machined flush with the inside diameter of the pipe.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Flow and Venturi Nozzles




The most commonly used standard is ISO 5167, which covers three types of classical venturi tubes:

A: Venturi tube with a cast convergent section

B: Venturi tube with machined convergent section

C: Venturi tube with a rough-welded sheet-iron convergent section

We can machine Type B venturis over inlet and outlet sections over the whole range of ISO 5167. Type C venturis are made out of a machined throat section and sheet steel inlet and outlet conesections. The throat section can be honed to achieve a smoother surface roughness. Type C venturis are reinforced with stiffeners and supplied with lifting lugs.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Venturi Tubes




To use the most common differential pressure meters the flow in the line needs to be as smooth as possible, i.e. without turbulence. Flow Straighteners are designed to remove swirl and to restore an acceptable reference profile geometry in a line where installing of sufficient straight length is not possible.

Depending on the amount of swirl and distortion and the allowable permanent pressure loss, several types of Flow Straighteners are available, such as ‘Zanker’, ‘Etoile’, ‘Sprenkle’, Tube-bundle, AMCA or AGA/ASME types.

We manufacture Flow Straighteners in any required material and dimension for any required pipe standard.

Download Product Sheet:

file pdf download acrobat adobe reader 44516    Flow Straightners

Contact us at  This email address is being protected from spambots. You need JavaScript enabled to view it.  for more product information.