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large pipe ring stiffness tester

large pipe ring stiffness tester

Model: RST-350/3100

Large pipe ring stiffness tester to determine the ring stiffness of circular cross-section thermoplastic pipes, the pipe range can be from 200mm to 4000mm or more. The nominal ring stiffness describes the resistance of a pipe to deformation by means of a vertically acting force. 

Conform with Standard ISO 9969, ISO 9967. ASTM D2412, EN1446, AS 1462.22


Feature of RST-3 series:

Suitable for large size pipe test (over 1000mm dia.);  computer control, three or more load cells.



General introduction

Ring stiffness testing machine is equipment used to measure the ring stiffness of thermoplastic plastic pipes and fiberglass pipes with a circular cross-section. This equipment is widely used for testing the ring stiffness, ring flexibility, flattening, bending, and weld tensile strength of pipes such as PE double-wall corrugated pipes, spiral-wound pipes, PVC pipes, and fiberglass pipes. Its working principle is based on the double-plate vertical compression testing method, which measures the force and deformation of the pipe at a constant deformation rate to determine the ring stiffness.


Large pipe ring stiffness tester to determine the ring stiffness of circular cross-section thermoplastic pipes, the pipe range can be from 200mm to 4000mm or more. The nominal ring stiffness describes the resistance of a pipe to deformation by means of a vertically acting force. 

Conform with Standard ISO 9969, ISO 9967. ASTM D2412, EN1446, AS 1462.22


Feature of RST-3 series:

Suitable for large size pipe test (over 1000mm ~ 3500mm dia.);  Robust structure frame, 4 columns+ 2 leading computer control, three or more load cells.


large pipe ring stiffness testerlarge pipe ring stiffness tester
Uniform 3 load cells for accuracy measuringGRP pipe ring stiffness test





Main Features

  • Key feature
  • Security function
  • Control system, Software
  • Standard

1, Two column design ensures high rigidity; 

2, Advanced closed loop AC servo control system increases the accuracy and control of the test sequence.  

3, For big pipe like 2m diameter, Three / Four load cells are connected in bridge, this strengthens the deflection resistance and improves the accuracy for tests on big diameter pipe. 

4, Our unique inner diameter measuring system makes mounting of even the largest pipe easy. 

5, The software is designed in-house and is very easy to use and runs on most modern computers. 

1), Sensor of position limitation switch; 

2), Emergency stop switch; 

3), Hardware driving system overload protection, over voltage, current protection;

4), Software over load protection. 

1), Based on full digital STC8800 measuring and control card; Data collection system use 4 channel of high accuracy 24 digit A/D conventer;

2), Real time load, deformation, corsshead displacement, test precess four kind close loop control;

3), Resolution can upto 1/500000, full range without step;

4), Level authorization management function: to improve sftware and data security, can set different password to realize several class authorization management. Different user with different right to operate the machine, avoiding unexpected mistake because human error.

5), PC control system, with advantage of high integration, reliable performance, easy adjusment etc. can real time collect test data, on-time display test curve,  test data file can be saved as ACCESS and SQL server, convenient for customer's data resource storage.

6), Automatically generate the testing report; the testing report can be displayed and printed, also it can be export in Excel/Access Format. Also, the user can edit the report format as requirement in report template;

7), Result recall function: after the test and saved, customer can open the test data and re-analysis at any time.

8), Results compare: observe several curve at same time, can fold curve or portion enlarge to analyze and compare sample characters.

9),Load~Time, Load~displacement, Displacement~time etc. curve smoothly switch, display test data, save, analysis and print.

ISO 9969  Thermoplastics pipes -- Determination of ring stiffness

ISO 9967  Thermoplastics pipes -- Determination of creep ratio

ASTM D2412 Standard Test Method for Determination of External Loading Characteristics of Plastic Pipe by Parallel-Plate Loading

EN 1446 Plastics piping and ducting systems - Thermoplastics pipes - Determination of ring flexibility

DIN 16961 Thermoplastics pipes and fittings with profiled wall and smooth pipe inside

AS/NZS 1462.22 Methods of test for plastics pipes and fittings Method 22: Thermoplastics pipes – Determination of ring stiffness

Main technical specification

Model: RST-3 seriesSuitable for small or middle size pipe test (1200mm ~ 3500mm dia.)
Max. load50Kn, 100Kn, 200KN
Load resolution0.01N
Load cell quantity3 pcs
Load accuracy±1% of reading value
Crosshead travel100mm-3700mm
Pipe Diameter range16mm to 3500mm
Speed range of crossbeam0.1 mm/min~500 mm/min, stepless, adjustable freely
Width of test space1150mm
Displacement accuracy0.001mm
Power220V/380V, 50Hz/60HZ
Pipe inner diameter measuring deviceYES
Creep Ratio Test(option)ISO 9967
Time range1~9999h59min59s
Timing resolution1s


Main Accessories

ItemQuantity
Frame1 set
   (include load cell, servo motor etc.,)
Compression platen (400*400mm)1 set
Pipe inner diameter measuring device1 set
Computer (English Win10)1 set
Professional ring stiffness test software (English)1 set
Documents (Manual, packing list, certificate)



Standard

ISO 9969 Ring stiffness testing for plastic pipe

ISO 9969 specifies a test method for determining the ring stiffness of thermoplastics pipes having a circular cross section. 

ISO 9969 requires that at least three samples are taken from the same pipe and labeled A, B and C. These samples are then compressed to at least 3% of the Inner Diameter and ring stiffness calculated for each sample. The ring stiffness is calculated as an average of these calculations. 


The initial ring stiffness or ring stiffness to ISO 9969 or ASTM D2412 characterizes the resistance of a pipe section to radial compressive forces. The measurement occurs at low deformations of 3%.

ISO 9967 Creep Ratio Test for Thermoplastic Pipes

ISO 9967:2016 Thermoplastics pipes — Determination of creep ratio

This standard specifies a method for determining the creep ratio of thermoplastics pipes having a circular cross-section.


ISO 9967 Creep Ratio Test Machine for Thermoplastic Pipes 

The ISO 9967 test procedure begins by preparing a ring-shaped specimen from a thermoplastic pipe. The ring is typically cut to a length equal to the pipe's outer diameter and must be free of visible defects. Before testing, the sample is conditioned, usually at 23°C for at least 24 hours. During the test, the specimen is placed vertically between two flat, parallel plates in a compression testing machine. A constant external force is applied to the ring to compress it until a deformation equal to 3% of its mean diameter is reached. This loading should occur gradually, typically within one minute. The test apparatus must maintain this compressive load over an extended period, most commonly 10,000 hours, under controlled environmental conditions. The deformation of the ring is measured at defined intervals during the test using a precise displacement measurement device. Initial and long-term measurements are used to calculate the creep ratio. This ratio quantifies how much the ring deforms over time under constant load, which indicates the material's long-term behavior and suitability for buried, non-pressure pipe applications. Accurate time tracking and temperature control are critical throughout the process to ensure valid results. The test concludes by comparing the deformation at 30 minutes and at the final time point to calculate the creep ratio according to the formula provided in the ISO 9967 standard.

ASTM D2412 Plastic Pipe Deflection Testing by Compression Loading Test

ASTM D2412: Standard Test Method for Determination of External Loading Characteristics of Plastic Pipe by Parallel-Plate Loading


Plastic pipe compression test, or pipe ring stiffness tseter is a testing standard used to determine the stiffness and load deflection of plastic pipe. This summary is intended to help you understand the basic procedure and equipment required to complete this test with accuracy.


ASTM D2412 test method covers the determination of load-deflection characteristics of plastic pipe under parallel-plate loading. 


Why do plastic pipes need to execute the ring stiffness testing?

The main purpose of conducting ring stiffness tests on plastic pipes is to evaluate their resistance to deformation under external pressure, ensure that they can withstand external loads such as soil and pressure in practical applications, and avoid rupture or failure due to excessive deformation.  ‌


The role of ring stiffness test

The ring stiffness reflects the ability of the pipe to resist deformation when subjected to vertical compression, directly affecting its stability and durability. The experiment simulates the external pressure environment to test the load bearing capacity of the pipe under specific deformation (such as 3% deformation in the diameter direction), in order to determine its ring stiffness index.  ‌

Importance in practical applications


Ensure bearing capacity: Pipes with high ring stiffness deform less under soil pressure, which can reduce problems such as pipe misalignment and leakage caused by external pressure.  ‌

Extended service life: Unqualified ring stiffness may cause the pipeline to rupture due to excessive external pressure during use, shortening its service life.  ‌

Compliant with engineering standards: like China's "Test Method for Ring Stiffness of Plastic Pipes" (GB/T 9647) explicitly requires all types of pipes to undergo ring stiffness testing to ensure their mechanical properties meet national standards.

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Beijing United Test Co., Ltd.