Sigma Cylinders’ unwavering commitment to quality has become its trademark in a highly competitive industry, catapulting the company to the highest ranks.

Sophisticated designs, a rigorous manufacturing process, top international certifications, grueling testing, and a licensed in-house lab are some of the biggest contributors to quality that exceeds all expectations.

Highly particular about the finishing, the performance and life cycle of the cylinders is assured, taking into consideration harsh environmental factors and the demanding daily usage of the cylinders. Because the entire product line is produced internally, using raw material of the highest quality only, Sigma can guarantee every cylinder, providing pre and post-sale assistance for the smoothest customer experience possible.

ISO Certifications & Quality Records

At Sigma Cylinders, comprehensive quality records are kept using a methodical system and following ISO 9001 standards. This allows the company to keep a clear register of performance, test results and reports for easy access and improved output. The records include documentation procedures, production and testing results, material marking, and personnel qualifications. 


The precision with which these records are kept has allowed Sigma Cylinders to obtain various ISO certifications that both guide its process and vouch for its commitment to the highest quality and safety.

ISO 9001 - Quality Management System

Aligned with the organization’s purpose and strategic direction, the Quality Management System (QMS) certification (ISO9001:2015) is the collection of all Sigma Cylinders’ processes and resources focused on consistently meeting customer requirements and ensuring their satisfaction.

ISO 3834 – International Standard for the Fusion Welding of Metallic Materials

Applicable inspections and tests are implemented at appropriate points in the manufacturing process to ensure conformity with contract requirements. Location and frequency of such inspections and/or tests depend on the contract and/or product standard.

ISO 14001 – Effective Environmental Management System (EMS)

ISO 14001:2015 specifies the requirements for an environmental management system that all Sigma Cylinders’ departments adhere to and can use to enhance their environmental performance. A separate certificate for waste management has also been obtained. One of the various environmentally-conscious initiatives launched by Sigma Cylinders is the latest decision to introduce a recycling procedure for the LPG Cylinder paint.  

ISO 45001 – Management Systems of Occupational Health & Safety (OH&S)

The ISO 45001:2018 guidelines enable organizations to provide safe and healthy workplaces by preventing work-related injury and ill-health. At Sigma Cylinders an emergency plan is implemented, in order to ensure the maximum safety of staff and visitors alike. 


Lab & Testing

In the world of LPG cylinder manufacturing, nothing is more vital than safety. Thus testing is important at every stage of the process and ensures the leading quality of the Sigma product line.

All our four labs in each country are officially approved and certified by governmental related entities. Our in-house state-of-the-art facility can perform destructive and non-destructive lab tests on raw material and in-production batch samples.

All the machinery are calibrated and certified to guarantee consistency. Quality Control officers inspect the process and also perform batch sample tests in the lab on raw material. Sample cylinders are produced and tested as well to ensure consistency and quality based on specifications of the client and standards, before proceeding to production. 

In total, there are 18 tests performed, divided into two categories:

Destructive Tests:

Before using the steel material, while the fatigue life of the cylinder and its failures, accidents, and costs, destructive tests are an excellent way to test the material performance of Sigma’s products. Through Burst Tests, for example, safety is proved by pressurizing LPG cylinders until they fail. The higher the threshold, the safer the cylinders. Of course, before using sheet material, it is periodically tested, both mechanically and chemically, while the fatigue life and its failure locations are verified through the Design Test.

Non-Destructive Tests:

Non-destructive tests include coating tests to determine if the zinc and paint will adhere properly through radiographic examination, salt spray, and scratch tests to reinsure weld and coating imperfections. 

Sigma Specialists

Designers & Engineers:

Responsible for precise calculations and designs based on the initial client drawings briefing.


Certified Quality Officers & Engineers:

Dispersed throughout the factory, the quality control officers are at the frontline, inspecting, testing, and detecting even the most minute of imperfections.

- Traceability in the production line

- Data Analysis

- Lab

Third-party independent and government inspection bodies:

Regularly monitoring and inspecting every single aspect of the process to make sure Sigma remains perfectly in line with their specifications and guidelines.  

Welding Safety Procedures & In Line Traceability

As part of the continuous quality control, inspections are rigorously performed before, during and after welding. This is particularly important in order to maintain detailed logs for traceability purposes.

For all welding processes, the stage is set by ensuring preparation and perfect working conditions. During welding, continuous monitoring and inspections at regular intervals take place. After welding, compliance with relevant acceptance criteria is strictly examined.