High Collapse grades cover the full range of sizes and weights from 4 1/2" to 26", grades from 80 ksi to 150 ksi, and offer special drifts on a standard basis without collapse derating. While strictly compliant with API standards, Vallourec High Collapse grades are delivered with the guarantee of their minimum High Collapse rating.
Combining High Collapse and Sour Service
HCSS series "Enhanced API":
Collapse loads can be due to well load cases, such as cementing operations, full evacuation, and APB (Annular Pressure Build up), or due to floating formations (mainly salt).
Vallourec Collapse calculation model
Vallourec started long ago to accumulate collapse testing data in order to understand the collapse phenomenon and its influencing factors. This extensive knowledge is consolidated within the Vallourec proprietary collapse model as a function of the influencing parameters.
It has demonstrated its prediction accuracy through extensive correlation and state-of-the-art statistical analysis. This robust formula enables to provide customers with a safe guaranteed high collapse value for a large catalogue of products.
Strength ksi (MPa)
Sulfide Stress Cracking resistance
NACE TM0177 SSC test
Min K1SSC value Average MPa√m (ksi√in)
More than 3,000 collapse tests have been performed on Vallourec High Collapse pipes. These tests are done in compliance with API 5C3 collapse test procedure.
Collapse tests are regularly done for R&D purpose but also on production samples. The collapse tests during production are requested by some customers to demonstrate the guaranteed ratings. They are done in-house or at external labs, at a given frequency (1 every 200 pipes for instance) specified by the customer.
Vallourec High collapse products are widely used in the following areas:
Please refer to the VAM® BOOK and API RP5C1.