hidden defects in fittings

7/31/2019 Hidden Defects in Fittings

1/3

HIDDEN DEFECTS IN FITTINGS

Reported by: Shell Chemicals, SNC Moerdijk

Large bore flanges and fittings that were delivered in a critical phase of a multi-million

project had to be rejected because of unusual and possibly concealed manufacturing defects.

In this stage, the project can only be continued at the expense of very high cost and effort.

Currently SNC Moerdijk is implementing a 10 million+ project in the MSPO-2 unit. For these

projects numerous piping materials have to be supplied, diameters ranging up to 56. Mostmaterials are made of AISI 316L stainless steel.

Initially some issues were encountered on a shipment of 40 flanges, where cracking was

observed visually. Follow-up inspections with dye penetrant testing further revealed that 10out of 60 flanges had crack indications. Metallurgical investigations confirmed that cracking

was caused by forging defects. Moreover, the investigations showed that cracking was

concealed by welding! (see figure 1). The whole shipment had to be rejected. Themanufacturer of the flanges is: Wenzhou Fada Flange Co Ltd, Wenzhou PRC.

In parallel, another shipment was received of fittings, sizes 8and larger, including

longitudinally welded fittings Since materials certificates and test reports were incomplete,additional acceptance tests were performed. These tests not only revealed that unacceptable

welding defects were found on welds that were approved by the notified body, there were

additional welds too! (see figures 2 and 3). With further investigation it became clear that the

majority of the fittings appeared to have additional welds, as if they were assembled bypieces. The certificates did not mention any additional welds, nor repairs and were witnessed

and approved by the NoBo (!). Also, while the longitudinal welds were visible, the additionalwelds were so well concealed that they could only be found by eddy current testing. Again,

the whole shipment was rejected. The manufacturer of the fittings is: Shanghai Want Industry

Co Ltd, Shanghai, PRC.

Although further investigation would be needed to detect all backgrounds and causes, the

findings are striking and the impression of intentional deception is hard to avoid in both cases.

Needless to say that it is very unfortunate that these issues become evident in a critical stageand jeopardize the whole project, since finding replacement parts of this diameter on the very

short term is extremely difficult. Furthermore, some fittings and flanges were already

installed and had to be cut out.

Nevertheless, if these materials would have been installed without detection of these defects,

consequences would without any doubt have been disastrous: potential of very serious

process safety incidents and loss of production of months!

Actions taken:

All rejected materials have to be replaced at the expense of very high costs and

efforts. Failing to install correct materials on time, will stop the project with multi-

million regret cost.

The issue will be included in a Business Control Incident that will be submitted. Liability of the supplier will be established and followed through (again at the

expense of cost and time).

The above incident triggers existential questions on the effectiveness of the procurement

process, quality assurance and the policy to rely on the QA system of manufacturers andsuppliers:

How effective is the quality assurance system of our supply chain?

What actions do YOU take to prevent this from happening?


2/3

Figure 1. Weld covering defect in flange

Figure 2. 24elbow, with dotted line indicating additional weld as detected by Eddy Current

and confirmed by metallography.


3/3

hidden defects in fittings

Documents