China 3cr12 Stainless Steel Suppliers – Reference Material For Physical Testing – Shandong Institute of Metallurgical Science

Each coal was air dried, reduced in size to <0.2mm, homogenized and packaged into individual bottled units.

Table 1 Certified values and Uncertainty for coal  July-01-2021 to  June -30-2022

Note: * Indicates that it is not within the recommended scope for production proficiency of CNAS

The homogeneity test was done on the bottled units by determination of ash and sulfur. The minimum weight of sample taken for analysis is 1.0g (ash) or 0.05g (sulfur). Variance analysis showed that the variability among different bottles was not significantly different from the variability between replicate determinations.

The validation of the certified values is one year. The certification will be performed for every year once revised certified values can be issued on application by Shandong Institute of Metallurgical Science Co., Ltd.

Characterization of methods using two or more methods of demonstrable accuracy in 9 competent laboratories. 

The certification analyses were performed using the Chinese National Standard （GB） methods by several qualified laboratories.

The certified value was expressed as X_T±U, where X_T is the mean value and U is the expanded uncertainty (95% confidence level). The uncertainty actually given in table 1 includes allowance for sample degradation within one year.

The statistical analysis and overall direction and coordination of the technical measurements leading to certification were performed by Shandong Institute of Metallurgical Science Co., Ltd.

Before characterization of 9 qualified laboratories, the instruments and equipment used shall be verified or calibrated, and certified reference materials shall be used for monitoring during characterization to ensure the traceability of reference materials.

1) These certified reference materials are packed in a brown glass bottle. Each weights 50g.

2) The bottle containing the materials must be kept tightly stopped and stored in cold and dry place, and opened only when necessary.

3) All data are expressed on dry bases. The moisture (moisture in the general analysis test sample) used for calculating the data on dry bases are determined according to moisture analysis method in GB/T 212-2008 “Proximate Analysis of Coal”.

4) The values given in table 1 of this certificate are those determined on July-01-2021 for CRM.