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D6315-98 – Standard Test Method Technical Guide
📐 Overview and Scope of ASTM D6315-98
ASTM D6315-98e1 standardizes the procedure for manually obtaining a gross sample from the surface layer of coal contained in barges. This practice is intended for general analysis, quality estimation, and total moisture determination. Following collection, the gross sample must be crushed and further prepared for analysis in strict accordance with Test Method D 2013.
Critical Caveat: A fundamental limitation of this standard is that the samples obtained do not satisfy the minimum requirements for probability sampling. Statistical inferences such as precision, standard error, or bias must not be calculated from these results. This method is reserved exclusively for situations where probability sampling methods are not feasible.
⚠️ Depth Warning: This practice strictly limits sampling to the top 18 to 24 inches (46 to 61 cm) of the barge load. The user is explicitly cautioned that samples obtained via this method do not typify material below the point of penetration.
| 🟦 Parameter | 📏 Specification |
|---|---|
| Standard Designation | D 6315 – 98e1 |
| Sampling Depth Limit | 18 – 24 in. (46 – 61 cm) |
| Sample Preparation Method | Per Test Method D 2013 |
| Statistical Validity | Not for probability sampling (See E 105) |
⚙️ Sampling Procedure and Agreement Requirements
Section 6 of the practice dictates that before any sampling occurs, all parties with an interest in the outcome must reach a formal agreement on all relevant details of the process. It is strongly preferred that this agreement be documented in writing to avoid future disputes regarding the validity of the sampling campaign.
| 📐 Required Agreement Item | ⚡ Details |
|---|---|
| Lot Size | The total quantity of coal represented by the sample must be defined. |
| Increment Characteristics | The exact number and mass of the increments to be collected. |
| Collection Device | The size, shape, and method of manipulation of the increment collection tool. |
| Sampling Location | The precise site(s) on the barge surface where increments are taken. |
| Suspension Criteria | Conditions under which increment collection may be suspended (e.g., adverse weather). |
| Safety Precautions | Specific safety and health practices to protect the sampling personnel. |
Addressing Layered Coal: A specific caution is given regarding barges loaded in passes or stages. If different coals or quality variations are suspected, the standard explicitly states that the barge should not be sampled via this top method. Instead, it must be sampled as it is unloaded using Conditions A or B outlined in Practice D 2234 to ensure a truly representative sample is obtained.
📊 Significance, Use, and Key Referenced Standards
The guidelines presented in D6315-98 serve to aid in the proper planning and execution of barge top sampling, accounting for the wide variety of conditions encountered in marine coal transport. When all parties have formally concurred, these procedures yield a gross sample from the top layer for necessary laboratory estimations. The following standards are essential companions to this practice:
- D 121 – Terminology of Coal and Coke
- D 2013 – Method of Preparing Coal Samples for Analysis
- D 2234 – Practice for Collection of a Gross Sample of Coal
- D 4749 – Test Method for Sieve Analysis of Coal
- E 105 – Practice for Probability Sampling of Materials
💡 Best Practice Tip: Always consult Terminology D 121 for formal definitions of terms like “gross sample” and “increment.” Ensure the collected gross sample is properly prepared using D 2013 before any laboratory analysis takes place to maintain chain of custody and data quality.
❓ Frequently Asked Questions
🔍 What is the primary limitation of ASTM D6315-98?
Samples obtained using this practice only represent the top 18 to 24 inches (46 to 61 cm) of the coal. Furthermore, this method does not satisfy probability sampling standards; therefore, it cannot be used to calculate statistical precision or bias.
💡 When should this practice be used instead of D 2234?
This top-sampling practice should only be utilized when probability sampling is not possible (e.g., accessing a loaded barge where mechanical sampling during unloading is not feasible). It is strictly a convenience method agreed upon by all interested parties.
⚡ What must all parties agree on before sampling begins?
Per Section 6.1, parties must formally agree on the lot size; number and mass of increments; size, shape, and manipulation of the collection device; increment location; suspension criteria; and safety precautions. A written agreement is strongly recommended by the standard.
📌 How does the standard handle barges with layered coal?
The standard explicitly cautions that top sampling cannot typify layered material. If different quality coal is suspected from different loading passes, the barge must be sampled during unloading using Conditions A or B in D 2234 to ensure full-depth representativeness.