GB/T 6683.4-2026 Pending National standards

GB/T 6683.4-2026 Petroleum and related products—Precision of measurement methods and results—Part 4:Use of statistical control charts to validate 'in-statistical-control' status for the execution of a test method standard in a single laboratory

Publish Date: 2026-03-31 Implement Date: 2026-10-01 For services related to genuine standard inquiry, procurement, translation, and other related services in China, please Contact Us

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Basic Information

Standard Code: GB/T 6683.4-2026

Standard Type: National standards

Standard Status: Pending

is_force_gb: no

CCS Name: Petroleum products

ICS Name: Integrated oil products

Publish Date: 2026-03-31

Implement Date: 2026-10-01

Pages: 40 pages

Scope

This document describes the process and methods for constructing, running, and maintaining statistical control charts to evaluate whether the laboratory's execution of experimental method standards is in a statistically controlled state, and how to establish and confirm the "statistically controlled" state. The content includes: single-value control charts (I charts), moving range control charts (MR charts) based on two samples, and exponentially weighted moving average (EWMA) single-value chart enhancement measures, as well as region-based operation rules [similar to Western Electric (WE) operation rules] single-value chart enhancement measures. This document is applicable to experimental methods related to major general cause variations and long-term, multi-operator conditions. The procedures presented in this document are primarily suitable for numerical results obtained from test quality control samples. The control samples come from homogeneous petroleum and related products, and the target characteristics of the control samples are maintained uniformity. If the test method allows, certified reference materials (CRMs) can be used as control samples, provided that the composition of the CRM can represent the tested materials and is not a pure compound; in this case, the CRM mean value should be obtained in this laboratory. This document is applicable to target characteristics that are known to be stable over time, as well as data sets with sufficient resolution to support the verification of the assumption that "the data distribution can be approximately represented by a normal (Gaussian) model". For cases where this assumption cannot be verified, corresponding optimization measures are proposed.