An Inspector Calls

Author: John van Voorbergen, Temati BV, The Netherlands.

Published in LNG Industry- june 2017

With temperatures of -167°C issues with insulation in the LNG industry can be costly and dangerous.

It all starts with the specification, where the right materials for these extreme temperatures must be specified. In Temati’s experience, however, the specifications are not usually the problem.

More attention should be paid to the application of the insulation itself. In cryogenic insulation the smallest mistake can cause after start up, and it is not easy to shut down an LNG installation for repair work.

Today we see a lot of external workers on site. Mainly because of the lower costs. However, they most part, they have little experience in cryogenic insulation and there is the risk of poor insulation techniques. Inspections of the quality of the applied insulation on site - or off site in case of pre-application – are a must on daily base. 

Last year, Temati was asked to inspect the insulation work on a LNG-Tank according to the specification and also according to the CINI. Several shortcomings were identified in the (pre-)insulated parts of the piping and equipment of the LNG Storage Tank.

Inspection of the LNG Tank insulation.

At the time of the inspection, it was below zero and yet there was no shelter/tent over the working place.

For most sealants, adhesives and tapes the temperature for application must be at least +5°C.

So, with no shelter or heaters, the environmental temperature was already a big problem at that time.

The Inspection also covered the insulation of pipelines and pipe supports.

In this case the insulation was in a very bad shape; metal cladding NOT in watershed position, screws/rivets going through the primary vapor barrier, no or incorrect staggering of the insulation, unprotected supports and exposed to weather conditions, and no correct fitting of the insulation parts/layers (even big gaps were found). Furthermore, almost all the insulation of the pipe supports was not correctly applied. There must be at least 50 mm distance from structural cradle to outer insulation joint to make sure the insulation can continue correctly. Also, there were no vapor stops, or they were applied incorrectly. On the vertical pipe lines the insulation itself was moving down, creating big gaps in the insulation. Typical for wrong or missing supporting rings.

A lot of insulation work was carried out at location off site, where it appears there were no inspections during application of the insulation. All problems found during inspection could have been handled during application, but there has to be an inspector on site to correct any problems found. This will prevent any problems such as those found during this inspection and can lead to significant cost savings.

Some samples of the problems found during inspection:

? Pipe support with undefined materials, gaps and no vapor stop (see below Figure 1).

? No staggered joints (see below Figure 2).

? Puncture of rivet through the primary vapor barrier (see below Figure 3).

? Gaps insulation pipe support, no vapor stop applied; outer insulation inside the cradle (Figure 4).

? Gap insulation vertical pipe (see below Figure 5).

In-Situ Foaming of Flange Boxes.

There are many ways to insulate the flange box in cold/cryogenic situations. Common practice is the use of polyisocyanurate (PIR)/ polyurethane (PUR) or Cellular Glass sections. Combinations of these materials are possible, but no matter what type of material is used, they must always fit the particular section for each valve box. This makes it difficult in case of inspections or repairs, because the size of the boxes are all different and need their own special shaped insulation sections. There is also the option to insulate the valve box with Handi-Foam - a two-component Polyurethane Foam - on site. The foam will spread out in the valve box and will give the best, uninterrupted insulation possible. The Lambda value of 0,023 W/m.K makes it a very good alternative for the standard insulation methods. As there is no need of special made parts for each valve box, it is very easy to insulate the individual valve. In addition to this inspection or repairs can be done immediately, without having to wait for each box.

To make sure it is also easy to take away the metal cladding after injection, the inside of the metal cladding will get a Vaseline coat. This will prevent the two-component polyurethane foam from adhering to the cladding and opening up the cladding for an inspection is easy. For cold/cryogenic applications the Handy Foam High Density (40 -45kg/m3) is used. Standard density of the Handi Foam is ± 28kg/m3.

The Handi Foam kits are ready to use, so no special tools are required. For working in cold environments, Temati can supply the heating belts to keep the Handi Foam kit at optimum operation temperature of ± 25°C.

To make sure the Handi Foam will get into every corner of the flange box, there have to be drilled some holes on strategic points in the cladding. After injecting the two-component foam, these holes can be closed with a simple plug.

Conclusion

Daily inspection on site and periodic job inspections by an independent insulation inspectorwill help to prevent a lot of problems and l;ead to significant sost savings