ASTM D 1598 test for long-term hydrostatic strength of plastic pipe

How ASTM D 1598 evaluates long-term hydrostatic strength of plastic pipe

Background and scope of ASTM D 1598

ASTM D 1598 is a standard test method that establishes the procedure to determine the long-term hydrostatic strength of plastic pipe materials. This method involves subjecting thermoplastic or reinforced thermosetting resin pipe to a constant internal water pressure at a fixed temperature, monitoring the time to failure. The results provide valuable information about the pipe’s ability to withstand prolonged stresses in service environments. The data generated is used by manufacturers, engineers, and quality control laboratories to assess material design life, compare formulations, and ensure compliance with specific product requirements.

Applies to plastic pipes including thermoplastics and reinforced thermosetting resins
Evaluates failure under constant internal hydraulic pressure at a specific temperature
Determines material performance and durability under extended use conditions

Key features of the procedure

Testing according to ASTM D 1598 requires use of conditioned pipe specimens, controlled pressure application, and precise temperature maintenance (commonly at 73°F/23°C unless otherwise specified). Each test sample is exposed continuously to the test pressure until it bursts or leaks. The elapsed time to failure is recorded and documented for statistical analysis. The average failure time offers insights into the expected service life of the pipe material under similar conditions encountered in real-world installations. This method is regularly used in both product development and production quality control processes to verify consistent pipe performance.

Applications and limitations

The method is particularly useful for qualifying new materials and verifying compliance to regulatory or contractual standards. However, results obtained are specific to the test environment and conditions such as sample preparation, temperature, pressure, and pipe diameter. As a result, test outcomes may not exactly predict in-field service performance but are useful in comparative material assessments and for setting quality benchmarks.

Takeaway

ASTM D 1598 provides a standardized approach for assessing the long-term internal pressure resistance of plastic pipes. This enables consistent product evaluation and enhances quality control across the industry.

Applicable to a range of plastic pipe types and sizes
Yields data on expected material lifespan under stress
Helps in quality control and product development
Enables comparison of different formulations and manufacturers

Detailed step by step guide to conducting ASTM D 1598 testing

Preparing pipe samples and ensuring test validity

Begin by selecting representative pipe specimens according to the standard’s sample preparation guidelines. Cut and clean the pipes to the required length, making sure both ends are square and free of irregularities. Condition the specimens as directed, typically to room temperature and the moisture level specified by ASTM D 1598. Inspect for visible defects before proceeding to testing, as imperfections can compromise the results.

Connecting and setting up testing apparatus

Install the test specimens in the hydrostatic pressure testing rig. Fit appropriate end closures and ensure leak-tight seals. Fill the pipe completely with water, eliminating all air pockets that could affect pressure readings. Set up the temperature control system to maintain the designated test temperature through the duration of the procedure.

Install the pipe horizontally unless there are specific instructions to the contrary
Ensure all connections and closures meet the sealing requirements outlined in the standard
Check calibration of pressure gauges and temperature monitoring devices

Applying pressure and monitoring duration to failure

Raise the internal water pressure to the specified test value as stated in ASTM D 1598, making sure to do so at a steady and controlled rate. Maintain this constant internal pressure and temperature, closely monitoring each sample for failure. Record the time at which a leak, rupture, or burst occurs for each specimen. Ensure accurate documentation of all observations, including environmental and equipment settings throughout the test run, for each sample tested.

Collecting data and performing analysis

After each pipe fails, determine the time to failure and note any relevant details about the nature of the failure (e.g., location, type of break). Organize the results and, if required, conduct statistical analysis to calculate the average and distribution of failure times. Use these findings to establish the material’s long-term hydrostatic pressure strength, supporting product certification or research objectives.

Record the pressure, temperature, and time to failure for each specimen
Collect failure observations in a consistent format
Analyze data according to standard statistical practices
Report test results as required for product validation or compliance
Maintain all documentation for traceability

Safety and maintenance considerations

Always follow laboratory safety protocols throughout testing, as the pressurized water and potential for pipe burst can present hazards. Ensure all personnel are trained on safe setup and shutdown procedures. After testing, depressurize equipment before removing specimens, and conduct regular maintenance on test rigs, seals, and monitoring devices to ensure future reliability and data accuracy.

Summary

Conducting ASTM D 1598 tests involves careful sample preparation, precise control of test conditions, and accurate monitoring of failure times. The procedure allows reliable determination of long-term hydrostatic strength for various plastic pipe materials.