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D1838-21 – Standard Test Method Technical Guide
This article provides a comprehensive technical overview of ASTM D1838-21, the Standard Test Method for Copper Strip Corrosion by Liquefied Petroleum (LP) Gases. This method is essential for detecting corrosive components that can attack copper and copper-alloy fittings in service equipment.
📖 Overview, Scope, and Significance
ASTM D1838-21 specifically targets the detection of corrosive constituents in liquefied petroleum gases. The primary significance of this test, as outlined in Section 5, is to ensure that copper and copper-alloy fittings used in storage, transportation, and utilization equipment do not experience deterioration during their service life. The test method is closely related to ASTM D130, which covers an equivalent copper strip test for less volatile petroleum products. Referenced standards include Practices D1265 and D3700 for sampling, Specification D1835 for LP Gases, and Adjunct ADJD0130 for the corrosion standard.
The test involves immersing a polished copper strip in approximately 100 mL of the sample at a temperature of 37.8 °C (100 °F) for 1 h in a cylinder of suitable working pressure. At the end of this period, the copper strip is removed and rated as one of the four classifications of the ASTM Copper Strip Corrosion Standard.
💡 Technical Note: While ASTM D1838 covers LP Gases, an equivalent test for less volatile petroleum products exists in Test Method D130. The specific construction of the stainless steel cylinder in D1838 is designed to safely handle the high vapor pressure of liquefied gases.
⚙️ Apparatus Requirements and Key Test Parameters
Test Cylinder Construction
The core apparatus is a corrosion test cylinder constructed of stainless steel with an O-ring removable top closure. The assembly must include a flexible inert hose, such as one composed of aluminum or stainless steel, to permit inverting the cylinder during the procedure. The entire assembly must withstand a minimum hydrostatic test pressure of 6900 kPa (1000 psig). No leak shall be discernible when tested at 3450 kPa (500 psig) with gas.
| 🟦 Parameter | 📐 Specification |
|---|---|
| Exposure Temperature | 37.8 °C (100 °F) |
| Exposure Duration | 1 Hour |
| Sample Volume | Approximately 100 mL |
| Min. Hydrostatic Test Pressure | 6900 kPa (1000 psig) |
| Leak Test Requirement | No leak at 3450 kPa (500 psig) |
Referenced Standards and Adjuncts
Proper execution of D1838-21 relies on several foundational documents. The table below summarizes the key references:
| 📄 Standard / Adjunct | 🎯 Title / Description |
|---|---|
| D130 | Corrosiveness to Copper from Petroleum Products (Copper Strip Test) |
| D1265 | Practice for Sampling Liquefied Petroleum (LP) Gases, Manual Method |
| D1835 | Specification for Liquefied Petroleum (LP) Gases |
| D3700 | Practice for Obtaining LPG Samples Using a Floating Piston Cylinder |
| ADJD0130 | ASTM Copper Strip Corrosion Standard for Petroleum (Visual Rating Standard) |
⚠️ Safety Warning: The user of this standard must establish appropriate safety, health, and environmental practices. Specific warning statements are provided in Sections 7.1, 10.3.1, and Annex A1 of the full standard. Due to the high pressure involved, the apparatus must be rigorously verified to withstand the specified 6900 kPa (1000 psig) hydrostatic test pressure before every use.
📊 Classification and Rating
At the conclusion of the 1-hour exposure period, the copper strip is removed from the sample cylinder. The appearance of the strip is carefully compared against the ASTM Copper Strip Corrosion Standard (ADJD0130). The strip is categorized into one of the four standard classifications, ranging from slight tarnish to severe corrosion. This rating directly determines the conformance of the LP gas batch regarding its corrosive potential to copper and copper alloys, which is critical for protecting valves, regulators, and piping in the distribution system.
❓ Frequently Asked Questions
🔍 What is the primary purpose of the D1838-21 standard?
It provides a standard test method for detecting the presence of components in liquefied petroleum gases that are corrosive to copper. This helps ensure the integrity of copper and copper-alloy fittings and connections commonly used in utilization, storage, and transportation equipment.
⚡ What are the exact test conditions specified in the method?
A polished copper strip is immersed in approximately 100 mL of the sample. The sealed cylinder is then held at a temperature of 37.8 °C (100 °F) for a duration of exactly 1 hour.
© 2026 TNLab — This article is a technical interpretation for reference only. The original standard as published by ASTM International takes precedence.