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Selecting alternatives for Viking-Johnson couplings (Sizes 6” through 24”)

PHASING OUT OF VIKING-JOHNSON COUPLINGS FROM THE PETROCHEMICAL INDUSTRY

Rechten: Alle rechten voorbehouden

Selecting alternatives for Viking-Johnson couplings (Sizes 6” through 24”)

PHASING OUT OF VIKING-JOHNSON COUPLINGS FROM THE PETROCHEMICAL INDUSTRY

Rechten: Alle rechten voorbehouden

Samenvatting

The local Dutch legislations (PGS-29) regarding the above-ground storage of flammable products have become stricter. This has led to the phasing out of Viking-Johnson couplings that are located inside of tank pits. These couplings are prone to leakage and they use rubber seals which are now prohibited by PGS-29. In the case of fire, the rubber seals could melt down, allowing the fire to reach the product inside of the pipeline which can lead a full-blown disaster.
The aim of this graduation thesis is twofold:
• • To create design options as alternatives for the Viking-Johnson couplings that comply with both the PGS-29 and the international process piping code (ASME B31.3) for the oil- and gas industry;
• • To create a selection matrix tool in Excel for selecting the best alternative in any given tank connection scenario.

The thesis approached this problem by first looking into the literature of piping design and pipe stress to find design solutions that could be used as alternatives for the Viking-Johnson couplings. This led to the formulation of design criteria that complied with the PGS-29 guidelines, the ASME B31.3 codes and all underlying codes specified therein. The found solutions can be summarized as following:
• • A straight pipeline to replace the coupling;
• • The use of elbows to create L-shaped pipelines and pipe loops to increase the flexibility;
• • The use of metallic expansion joints to replace the coupling.

A stress- and flexibility analysis was performed with Caesar II and Nozzle Pro to determine the minimum dimensions required of each alternative to prevent excessive nozzle stresses. The FEM analysis of Nozzle Pro concluded that pipelines larger than 16” became too heavy which lead to excessive stresses on the tank nozzle. To address this issue, it was recommended to design special supports to counteract this weight. The metallic expansion joints did not have this issue; they can be used for any tank settlement scenario and for any pipe size because of the inherent flexibility of the bellows. Due to time constraints, the stress- and flexibility calculations cover only pipelines where the point of rotation is located along the longitudinal axis of the tank nozzle. A follow-up project should determine the effects on the tank nozzle in cases where the point of rotation lays at an offset from the longitudinal axis. The effects of tank keeling on the tank connection should also be included in the scope of follow-up projects.
The selection matrix tool was created using Excel. The results of the stress- and flexibility analysis were saved into the database of this model. The scope of the model depends solely on the completeness of the database. Vicoma can fill the database through follow-up projects. To do this, it is essential to follow the analysis procedure established in the thesis for other pipe specs, having different process conditions and with different tank settlements. The selection matrix tool in its current state is able to select the best alternative for tank settlements of 200 mm, with design conditions of 18,66 bar(g) and 68 0C by using the Vic C-150 pipe specs (carbon steel – 150#).

Toon meer
OrganisatieDe Haagse Hogeschool
AfdelingTIS Werktuigbouwkunde
PartnersVicoma Engineering
Jaar2018
TypeBachelor
TaalEngels

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