Quality testing

A.D. Tubi Inossidabili’s strong point is the quality of the products we supply to our customers. From the very first days of the company it has always paid the utmost attention to the quality system and quality department with two in-house laboratories, fully equipped for both destructive and non-destructive testing, A.D. Tubi Inossidabili is in the position to immediately assess the quality of its production and to investigate any arising condition of the material.

Following the most stringent of requirements from standards that rule the production of our welded tubes, the company pride itself on the manufacture high quality products for the most demanding markets.

Duly certified as per

Italian production site:
ISO 9001:2015
AD2000 – Merkblatt W0
ISO 14001:2015
ISO 45001:2018
Pressure Equipment Directive 2014/68/EU Annex I

U.S.A. production site:
ISO 9001:2015

Manufacturer approvals by: Bureau Veritas – Lloyd’s Register – RINA – DNV GL – KR Register – Norsok M-650

A.D. Tubi Inossidabili can grant complete suitability of the products to customers’ needs. All manufactured tubes are technologically tested according to a QCP linked to every production. A full array of destructive + non-destructive tests guarantees the quality of the tubes, and the two in-house fully equipped laboratories allow to have immediate results assessing production quality from start to end.




Residual circumferential stresses test

ASTM E1928 Thirkell test
This test estimates the approximate residual circumferential stress in our tubes from the change in outside diameter that occurs upon splitting a length of the tube. A specimen with a length of approximately 100mm is longitudinally split, then the diameter is measured at 90° from the split. A.D. Tubi tubes have a very low residual stress.

Residual longitudinal stresses test

Tongue Test
The tongue test is performed if the order requirements foresee an evaluation of the residual stresses embedded longitudinally in the material due to mechanical work performed during the production of the tube itself. Three sides of a rectangle are cut from the tube and the opening of this “tongue” is measured and related to longitudinal stresses.

Burst test

Burst test is a test that can be carried out upon customer request to determine the burst pressure of tube. A sample of tube is filled with oil until it ruptures, at which, the pressure recorded. The location and shape of  the crack can give important information about the materials ductility.

Dimensional controls

Operators perform diameter, wall thickness and length control according to a frequency set in the production standard. All measurement gauges are certified and periodically calibrated. Upon customers’ request, also internal diameter can be measured using specific gauges.

Weld seam measurement

Height of the weld seam can be measured using a special gage. Internal height of the weld seam from inside bead rolled tubes, for common tubes, is typically under 0,05mm. External weld seam, when grinded, is close to zero.

Ultrasonic wall thickness measurement

Wall thickness can even be measured using an ultrasonic device for special applications.



Various corrosion tests can be performed in our laboratories in order to evaluate tubes corrosion resistance to intergranular, pitting and crevice corrosion or to detect the presence of intermetallic phases.

EN ISO 3651-1 (Huey Test)
EN ISO 3651-2 Pr.A – Pr.B – Pr.C
EN standard to determine the resistance to intergranular corrosion of stainless steels,
ferritic, austenitic and duplex materials.

ASTM A262 Pr.A – Pr.B – Pr.C – Pr.E – Pr.F
ASTM A763 Pr.X – Pr.Y – Pr.Z
ASTM A923 Pr.C
These standards specify Intergranular Test used to detect sensitization from slow cooling rates, insufficient annealing, and carbides precipitation. Rapid screening tests can also be carried out.

ASTM A249 S7 Weld decay test.
This test is used to evaluate the weld seams resistance in an acidic environment.
AD Tubi, depending on the material, can achieve a ratio R<1.

ASTM G28 Pr.A and Pr.B
ASTM G28 (also known as green death) is the standard test method for detecting susceptibility to intergranular corrosion in nickel-rich, chromium-bearing alloys.

ASTM G48 Pr.A – Pr.B – Pr.C – Pr.D – Pr.E – Pr.F
These tests are acid based pitting and crevice corrosion tests that are intended to mimic potential applications.
ASTM G48 is the standard method for pitting and crevice corrosion resistance of stainless steels and related alloys by use of ferric chloride solution.

Other corrosion tests can be carried out according to customers’ specification.