FAQ

It is impossible to imagine our modern-day society without synthetic materials. Over the past decades more and more traditional materials have been replaced by innovatively manufactured synthetics. This does not only save costs but also saves natural resources which eventually spares the environment. Synthetic industries are now in a position where they can develop synthetics with features for every specific application area. In the areas of gas- and water distribution, infrastructure and district heating these special synthetics have become indispensable. 

1a. Why not choose cast iron surface boxes?

Surface boxes made out of cast iron have proven to be robust and durable in the past. However, the negative characteristics of cast iron have always caused a lot of issues. Common issues are rust, clattering lids, frozen lids and inoperable surface boxes which eventually lead to extra maintenance and high costs. In the autumn, for example, cast iron surface boxes for hydrants need maintenance to prevent the surface box and lid to freeze together in the winter, which takes a substantial amount of time and money. These situations do not occur with synthetic surface boxes. Synthetic surface boxes are completely maintenance free!

1b. How well accepted are synthetic surface boxes?

Nowadays surface boxes made out of cast iron are already being replaced for synthetic surface boxes on large scale. The market share of synthetic surface boxes continues to grow. Our surface boxes are made out of a specially designed high quality plastics. We call this material P123. P123 is a polyamide 6.6 plastic which is strong, durable and impact-resistant. Many years in practice have proven the material to be very suitable for the job.  

1c. What are the advantages of synthetic surface boxes?

- Lightweight means light handling and light installation;

- no rattling lid;

- no force needed to place in or remove lid from housing;

- no sinking of the lid;

- small gaps around the lid can be restored if necessary; 

- lid does not rust up in housing;

- lid and housing do not freeze together;

- screwed and glued stainless steel locking bolt ensures that the lid cannot be lost easily; 

- synthetic surface boxes are resistant to bases and acids;

- synthetic surface boxes are recyclable.

The first thing to consider when choosing a surface box from scratch is the application area, which can be divided into two main categories: installation in tarmac and installation in pavement. Since we have the ability to develop surface boxes with special features for specific applications, like pavement installation, we do not only distinguish fixed height surface boxes from height adjustable surface boxes anymore. For almost every application area we offer a suitable synthetic surface box. The product finder could help you choose the right surface box for your situation. 

2a. What do I need to consider when installing a surface box in tarmac?

In tarmac roads height adjustable surface boxes are to be advised. When rolling in, the flexible top part can be aligned with the tarmac surface resulting in a perfect installation. When installing height adjustable surface boxes, the surrounding area has to be properly compacted in order to achieve a durable solution. The advantages of height adjustable synthetic surface boxes have convinced road construction companies and utilities for many years. However, this wouldn’t be the case if the installation manuals hadn’t been followed correctly. Therefore it is very important that all installation instructions are accurately observed before installation. Only a professional installation enables the surface box to meet all the expected requirements and ensures the durable solution that has been experienced for many years in practice. 

2b. Which advantages do height adjustable synthetic surface boxes have in tarmac roads?

Due to the clever and light weight design of the height adjustable synthetic surface box, it can be easily installed and quickly handled. During rolling, the top part is balanced and carried by the underlying tarmac layer and accurately aligned with the road surface. After correct installation issues like subsidence or exaltation of the surface box are not likely to occur.

2c. What do I need to consider when installing a surface box in roads other than tarmac? 

It is not advisable to install height adjustable surface boxes in surfaces other than tarmac. Undergrounds like sand, gravel or concrete, do not provide enough support for the top part of a height adjustable surface box. Therefore fixed height surface boxes are much more suitable for- and more often installed in- for example sidewalks, green areas or city squares. 

2d. Why are height adjustable surface boxes not really suitable for pavement (e.g. sidewalks)?

For professional installation the top part of a height adjustable surface box requires a bituminous underground like tarmac. The ground under pavement does not provide enough support for the top part. Undergrounds like sand, gravel or concrete, do not fixate the top part sufficiently resulting in a loose top part which in time can be easily pulled out. We also discourage screwing top and bottom part together. Choosing fixed height surface boxes would be the best option for these applications. When installing a surface box for water in pavement, please consider the pavement (P) variant for a quick installation and perfect fit. 

2e. Which surface box would be particularly suitable for my application? 

The product finder could help you choose the right surface box for your situation. A few recommendations are listed below.

- For installation in high traffic areas we recommend the “Swiss model”.  The Swiss model is height adjustable and extra robust in order to handle heavy traffic. 

- For installation in pavement we recommend fixed height surface boxes. For water applications our special water surface boxes for pavement (P) are particularly suitable. 

- To implement the “ZTV Asphalt StB07” (German regulations for i.a. the installation of surface boxes in tarmac) we recommend installing our recently developed height adjustable surface boxes with “Fugenring” (V-FUG).

Downloads
Leaflet Ideal installation GW EN

Our surface boxes can only fully fulfil their function when exactly installed as prescribed in the installation manuals. We regularly update our manuals to always adapt to practical situations and new technologies in road construction. Our installation manuals are detailed, practical and easy to use. For a professional installation it is very important that all instructions are followed carefully.

When a fixed height surface box gets installed in tarmac the surrounding area cannot be compacted optimally. Due to a low degree of compaction the surrounding area of the surface box is very likely to prolapse. The height of the surface box, however, remains unchanged allowing the surface box to protrude and causing noise pollution and damage to road and surface box when used by traffic.

- Only height adjustable synthetic surface boxes should be installed in machined road gaps;

- be aware that a height adjustable surface box always has to be installed 12 centimetres

lower than a fixed height surface box;

- note that the gap has to be big enough; make sure that the plate compactor has enough

room to compact the surrounding area of the surface box unobstructed;

- compact the foundation sufficiently;

- compact the gravel and tarmac layers very good;

- make sure that you use the installation manual specially made for the installation of height adjustable surface boxes in machined road gaps.

Downloads
GW Installation manual Height adjustable surface boxes in machined road gaps

The “Swiss model”, in German “Schweizer Modell”, was developed years ago in cooperation with leading Swiss utility companies. The top part of these surface boxes is significantly strengthened compared with the standard height adjustable version. The Swiss model is only available as height adjustable version and is available for both water and gas applications. The top of the Swiss model, which is visible after installation in tarmac, is more robust, stable and resilient. By tripling the size of the bearing surface there is much more support of the top part. This way the force on the body of the surface box (caused by traffic) is also reduced by a factor of three, sparing the surface box over time.

Downloads
Leaflet Swiss modell Gas GW EN
Leaflet Swiss modell W GW EN

Surface boxes for water applications are usually designed with a round top. In many cases these surface boxes are installed in pavement areas like sidewalks or city squares with square and rectangle pavement. For construction companies it is relatively time consuming to install surface boxes with a round or oval top in pavement and the result is often unattractive and instable. In addition to these issues, the surrounding area of a regular surface boxes installed in pavement can easily prolapse causing dangerous holes for pedestrians. To avoid problems like these we facilitate a lasting solution especially for pavement areas. Our surface boxes for pavement have a square or rectangle top so they can be perfectly installed in pavement and offer a more stable and aesthetic solution.

Downloads
GW Installation instructions for pavement EN
Leaflet surface boxes for pavement EN

Height adjustable surface boxes for hydrants have a slightly smaller inside space than fixed height surface boxes for hydrants. For some larger underground hydrants this narrow space can cause problems. Although the dimensions of the operation tools are always according to DIN, the outside dimensions of the underground hydrant may vary. Therefore it may occur that the inside space of the standard height adjustable surface box is not big enough for some underground hydrants. When a surface box is too small the hydrant disables the top part to lower sufficiently. Result: a proper installation is not possible. This issue applies to all surface boxes made for hydrants; it doesn’t matter whether it is a synthetic or cast iron surface box. Fortunately G+W has developed the type 4055V BR+, thereby offering a suitable solution for every type of underground hydrant.

The type 4056-2 surface box is significantly larger than surface boxes according to DIN 4056(-1). Previously this type was only available as cast iron surface box, but after many customer requests G+W has successfully developed a synthetic version of this surface box. The 4056-2 is available as fixed height or as height adjustable version and is mainly used in the water distribution networks of big cities. Many underground valves with a diameter larger than 250mm are installed here. When trying to operate valves bigger than 300mm diameter with a T-key, the regular type 4056 surface box offers insufficient inside space. This is not an issue when choosing the type 4056-2(V) of G+W.

Downloads
Leaflet 4056 2 GW EN

The ZTV Asphalt StB07 is a German guideline for tarmac road construction. It describes how tarmac roads should be constructed and requires, among other things, that there should always be an elastic and durable joint between road accessories and the road.

According to the ZTV Asphalt road accessories include all elements which can be installed in the surface of tarmac roads. Typical road accessories are surface boxes, sewer manholes, gutters and rain drains.

During installation hot tarmac is rolled on and around the surface box. Whether the surface box is made of synthetics, cast iron, granite or concrete, there is no physical joint between surface box and tarmac after installation. Over time gap formation can be a consequence. That is why installation of surface boxes in tarmac roads always requires special attention.

Years of seasonal temperature changes cause tarmac roads to expand and contract, which can lead to stresses in the surface and eventually small cracks. These small cracks enable water to enter and freeze when the temperature drops, eventually causing erosion and thus damage to the road. If this unfortunate event occurs the road has to be repaired or totally renovated which is obviously accompanied by high costs. A durable elastic joint between surface and surface box could avoid this. It works as a compensator and absorbs road stresses preventing the surface around the surface box to erode.

Downloads
Fachbericht Fugen und Nahte in Asphaltstrassen

When repairing a tarmac road, gaps are often machined into the surface which takes a lot of time and comes with great precision. It is often problematic to repair cracks, particularly in areas of limited size e.g. around surface boxes. The ZTV Fug.01 demands that a joint between road surface and surface box has to be approximately the same height as the lid and one centimetre wide. Due to the manual operation it is impossible to follow these requirements with consistent quality. Seams around the surface box are often made too shallow which disallows the joint to absorb enough stresses. Result: an ineffective joint.

G+W acknowledges the importance of the ZTV Asphalt StB07 guidelines. With our newly developed height adjustable synthetic surface boxes with integrated “Fugenring” (V-FUG) every road construction company will be able to produce a durable joint between surface and surface box. This means no time consuming and inaccurate sawing or milling is needed. After removing the ring automatically a gap arises which has to be filled with liquid tarmac, leaving an elastic joint that lasts. Construction companies have already successfully put this into practice eventually avoiding problems like erosion and tarmac rupture.

Downloads
Leaflet Fugenring GW EN

At G+W we think it is important to stay closely connected to our products, even after selling them. In our opinion, only those companies that take the effort to learn about the conditions of their products during and after installation, can continually improve their selves. Therefore close cooperation with our clients, in the sense of supporting and monitoring surface box installations, is part of our daily business. In addition we offer courses, instructions on site and other desired assistance. The mainspring of these services is to share our knowledge. This way we try to avoid as much errors as possible and achieve the highest level of quality.

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