ASTM D1066 provides a standard practice for extracting and transporting representative samples of saturated and superheated steam. The practice focuses on sampling-system design, including sampling-nozzle selection, nozzle location, sample-line design, flow control, and cooling or condensing requirements. Proper design helps laboratories obtain samples that accurately represent impurities present in process steam, including dissolved chemicals, solid particles, chemicals associated with particles, and water droplets. ASTM D1066 (Standard Practice for Sampling Steam) focuses on representative sampling, ideally isokinetic, since nonrepresentative extraction may alter the amount of impurities reaching the analytical system. Sodium, silica, iron, copper, and cation analysis are commonly used to measure steam purity, and this information can be used to assess corrosion, solid-particle erosion, flow-accelerated corrosion, and deposit formation in downstream devices like turbines and process heat exchangers.
Get Certified ASTM D1066 Testing for Reliable Steam Sampling and Purity Evaluation
ASTM D1066 can assist laboratories and power generation facilities in developing representative steam sampling systems. Skilled personnel design sampling nozzles and sample lines according to the steam-flow conditions. Technicians manage sample transport and cooling to minimize contamination, deposition, and compositional changes. Representative samples make the chemical and purity analysis more reliable.
What is the scope of ASTM D1066?
ASTM D1066 covers sampling of both saturated and superheated steam. It applies to steam generated in fossil-fired boilers, nuclear boilers, and other processes, where adequate pressure is present to allow representative sample steam to flow. It also provides guidance for lower and subatmospheric pressure steam, where suitable means are provided in the sampling system to establish representative flow.
Material: Saturated and superheated steam from boilers and other process systems.Â
Objective: Extract and transport a representative portion of the steam for subsequent analysis.Â
Property measurement: The practice itself does not measure impurities; it provides a representative sample for determining steam impurities such as sodium, silica, iron, copper, and cation conductivity.Â
Method: Isokinetic or suitably constructed steam extraction with subsequent controlled transport, cooling, and condensation as needed.Â
Result: A condensed steam sample or steam sample for chemical or purity analysis. Sample unrepresentation by non-isokinetic extraction, particle or droplet stratification, condensation at inappropriate sites, deposition within sample lines, or lack of flow control.Â
Environmental conditions: Steam sampling involves potentially high temperature and pressure, so personnel must establish appropriate safety, health, and environmental practices.Â
Applications: Boiler and steam system monitoring, assessment of steam purity, turbine protection, process heat exchanger monitoring, and study of corrosion, erosion, and deposition issues.
What are the uses of ASTM D1066 testing?
ASTM D1066 allows for representative steam sampling before chemical and/or purity analysis at the laboratory. Proper sampling allows analytical results to reflect the actual process-steam condition rather than contamination or losses introduced by the sampling system. This standard-
Supports representative sampling of superheated steam.Â
Guides isokinetic sampling.
Helps control sample-line deposition and condensation effects.Â
Facilitates representative sampling of dissolved and particulate contaminants.Â
Provides reliable steam-purity monitoring to help protect downstream turbines and heat exchangers.Â
Guides sampling-nozzle location, construction, sizing, and sample transport.
Which Materials Can Be Tested Under ASTM D1066?
ASTM D1066 is applicable to steam, saturated and superheated steam. The steam is generated in fossil-fired boilers, nuclear boilers, or other process systems. The practice can further be implemented at subatmospheric or low pressures when the system draws a representative sample flow.
Why is ASTM D1066 Important?
The quality of the steam is highly dependent on the way the staff takes and move the sample. If the sampling nozzle does not capture the same velocity distribution as the process stream, suspended particles and liquid droplets may enter the sample at proportions different from those in the steam line. So non-isokinetic sampling can result in false analytical conclusions.
ASTM D1066 Equipment and Sample Preparation Guide
ASTM D1066 focuses on the design of the sampling system rather than the preparation of a conventional laboratory specimen. The sampling assembly should ensure a representative flow of material from the flow pipe to the nozzle, isolation valves, tubes, cooler or condenser, and sample point.
The sample consists of saturated or superheated steam extracted directly from the process pipe through a representative sampling nozzle.
Sample Preparation
Personnel design the sampling system for representative extraction and transport. Superheated steam should be cooled immediately after extraction when required to prevent contaminant deposition during transport.
Specimen Dimension
The smallest recommended sample-port diameter is 3.18 mm (1/8 in.), while ports below 2.38 mm (3/32 in.) should not be used because of plugging risk.
Instrumentation
Equipment includes an isokinetic sampling nozzle, isolation valve(s), sample tubing, and primary sample cooler or condenser, flow-control components, and appropriate downstream sampling or analytical equipment.
Testing Procedures and Requirements for ASTM D1066
ASTM D1066 does not provide a conventional laboratory testing sequence for measuring a property. Section 8.1 specifically identifies the practice as an equipment-design practice rather than an operating procedure. The main task is to design a sampling system that can extract and carry steam without significantly altering its composition. Other reference ASTM documents include A269, A335, D1129, D3370, and D5540. The complete sampling-system design process for ASTM D1066 includes:
Personnel establish whether the process contains saturated or superheated steam and determine the operating pressure, temperature, velocity, and expected particulate or moisture conditions.
Sampling Location Selection and Nozzle Design
Engineers select a location that minimizes flow disturbances and stratification. Personnel design the sampling nozzle for representative, preferably isokinetic extraction. The nozzle must withstand flow-induced vibration, thermal stress, and other mechanical loads.
Sample-Port Sizing, Flow, and Nozzle Position
Analysts and engineers determine the port size from the required sampling rate, steam velocity, and density. Personnel position the nozzle away from the pipe wall to obtain a representative velocity region.
Sample-Line Design
Engineers size and route the sample tubing to maintain suitable flow and minimize deposition, condensation, sharp bends, dips, low points, and pockets where solids or liquid can accumulate.
Cooling and Condensation
Personnel cool saturated steam appropriately and rapidly cool superheated steam after extraction when necessary.
Sample Delivery
The system transports the sample to the cooler, condenser, analyzer, or grab-sample point while maintaining representative composition.
ASTM D1066 Testing Process and Data Collection
During ASTM D1066 sampling-system design, engineers document the steam condition, process-pipe dimensions, sampling location, nozzle configuration, calculated sampling rate, sample-port size, sample-line arrangement, cooling or condensation system, and relevant operating conditions. Analysts then use the collected steam or condensed sample for the applicable chemical analysis. The next analytical method is not specified in ASTM D1066.
ASTM D1066 Testing Using Isokinetic Sampling Nozzle
Common Challenges and Troubleshooting
The principal challenge in ASTM D1066 sampling is maintaining sample representativeness from the process pipe through the analytical sampling point. The concentration of impurities reaching the analyzer can change due to non-isokinetic extraction, pipe-wall effects, stratification, premature condensation, and deposition within the sample line. For saturated steam, personnel should avoid sampling locations where moisture films can accumulate impurities. For superheated steam, they should cool the sample promptly after extraction to reduce contaminant deposition as pressure and temperature decrease. Engineers should also avoid traps, pockets, sharp bends, dips, and low points in the sample line because these locations can collect solids or condensate and later release them when operating conditions change.
ASTM D1066 Analysis Results and Interpretation
ASTM D1066 is not an independent numerical analytical result, since it sets the sampling system, not the later chemical analysis. The quality of the collected sample directly affects the reliability of measurements performed for steam impurities such as sodium, silica, iron, copper, and cation conductivity.
Laboratories report the measured steam-impurity values obtained from the representative sample using the applicable analytical ASTM method and appropriate units.Â
Technicians record the primary analytical result together with the steam source, sampling location, sample condition, and relevant sampling-system information.Â
Analysts document the nozzle configuration, sample-line arrangement, sampling rate, cooling or condensation conditions, and observations that could affect sample representativeness.
Engineers and analysts compare the measured steam-purity results with applicable boiler, turbine, process-equipment, or project requirements and investigate conditions associated with corrosion, erosion, or deposit buildup.
ASTM D1066 does not directly measure chemical property. It provides practice for obtaining representative samples of saturated and superheated steam so laboratories can subsequently analyze steam impurities.
What type of steam does ASTM D1066 cover?
The practice covers both saturated steam and superheated steam from fossil-fired boilers, nuclear boilers, and other process systems.
Why is isokinetic sampling important?
Isokinetic sampling matches the velocity vector entering the sampling nozzle with the velocity vector of the process stream. This helps obtain representative concentrations of dissolved chemicals, particles, and water droplets.
Davis Scott is an Electrical and Electronics Engineer specializing in multidisciplinary validation, quality assurance, and comprehensive electro-mechanical testing. Know More
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