Technical Blog
Engineering insights on sample probe assemblies, material selection, ASME standards, and pipeline instrumentation.
Barlow's Formula and Hoop Stress for Sample Probe Tube Design
First-principles derivation of Barlow's formula for hoop stress in thin-walled probe tubes. Worked examples for 316L, Hastelloy C276, and Inconel 625 across the standard OD and wall thickness range.
Chloride Pitting in 316L Sample Probes: Temperature, Concentration, and Upgrade Paths
Engineering chart of chloride pitting limits for 316L sample probes. The temperature × concentration safe envelope, when to upgrade to duplex or nickel alloy, and how to read a Tsujikawa-style pitting diagram.
Custody Transfer Sampling per API 14.1 and GPA 2166
Engineering and regulatory guide to custody transfer sampling of natural gas. API 14.1 spot, composite, and online sampling methodologies, GPA 2166 quality requirements, and probe design implications for fiscal metering.
Preventing Carryover and Cross-Contamination in High-Throughput ELISA and Immunoassay
Engineering approaches to carryover prevention in ELISA, CLIA, and immunoassay autosampler probes. Wash protocols, probe materials, geometry, and the role of SilcoNert and PEEK in achieving < 0.1% carryover.
Hastelloy C276 vs Inconel 625: Sample Probe Material Selection for Aggressive Service
Direct head-to-head comparison of Hastelloy C276 and Inconel 625 for sample probe assemblies. Pitting resistance equivalent (PREN), chloride limits, sour service compliance, weldability, and cost tradeoffs.
Hydrogen Embrittlement of Sample Probes in High-Pressure H2 Service
Engineering guide to hydrogen embrittlement risk for sample probes in hydrogen pipelines, refinery hydrotreaters, and hydrogen storage systems. Susceptible alloys, mitigation strategies, and material selection for the hydrogen economy.
ISO 10715 Natural Gas Sampling: International Practice for Pipeline and Custody Sampling
Explainer on ISO 10715 — the international standard for natural gas sampling. Comparison with API 14.1 and GPA 2166, sample line design rules, probe requirements, and the dew-point trap problem.
Isokinetic Sampling: Theory, Probe Design, and When You Need It
Engineering guide to isokinetic sampling for particulate-laden gas and liquid streams. Theory, probe nozzle sizing, velocity matching, EPA Method 5, ASME PTC 38, and design tradeoffs.
NACE MR0175 / ISO 15156 Compliance for Sample Probes in Sour Service
How to specify NACE MR0175 / ISO 15156-compliant sample probe assemblies for H2S service. Material restrictions, hardness limits, heat treatment requirements, and the difference between MR0175 and MR0103.
The Definitive Guide to Probe Cycle Life and Preventative Cleaning
A complete engineering guide to sample probe cycle life: contact resistance drift, flux buildup, oxidation, tip punch-through, and a preventative cleaning schedule that extends mean-time-between-failure for industrial and clinical sampling probes.
Reynolds, Strouhal, and the Physics of Vortex Shedding for Sample Probes
First-principles guide to the dimensionless numbers that govern vortex-induced vibration of sample probe assemblies. Reynolds number flow regimes, Strouhal correlations, lock-in resonance, and Scruton number damping criteria.
Stainless Steel vs PEEK in Harsh Chemistry: Material Selection with the Weber Number
When PEEK beats 316L for chemical sampling and when 316L beats PEEK. Mechanical strength vs chemical inertness, the Weber number for atomization and droplet impact, and the role of biocompatibility.
Sulfide Stress Cracking in Sour Crude Sampling: Mechanism and Mitigation
How sulfide stress cracking destroys sample probes in sour crude and sour gas service. Mechanism, susceptible alloys, NACE MR0175 mitigation, and probe design choices that extend life in H2S-bearing streams.
Tantalum and Zirconium Sample Probes for Extreme Acid Service
When standard nickel alloys aren't enough: tantalum and zirconium probe assemblies for hot concentrated sulfuric, hydrochloric, nitric, and phosphoric acid service. Cost, fabrication, and performance tradeoffs.
Thermowell vs Sample Probe: Geometry, Standards, and When to Use Each
Side-by-side comparison of thermowells and sample probe assemblies. Same physics, different purpose. ASME PTC 19.3 applies to both. When the two get specified together, and when one substitutes for the other.
Minimizing Time Delay in Online Process Analyzer Sampling Systems
Engineering guide to reducing transport lag in online process analyzer sampling — gas chromatographs, mass specs, NIR. Sample line sizing, dead volume, fast loops, and the residence time vs detection limit tradeoff.
PG Gland Connection Types: NPT, Socket Weld, Flanged, and Welded Options
Complete guide to PG packing gland connection types including NPT, socket weld, threaded flange, and welded flange. Covers sealant selection, body materials, special options, and torque specifications.
Probe End Types: V-Notch, Plain Cut, Integral NPT, and Custom Configurations
Technical guide to sample probe end types including plain cut, V-notch, integral NPT, and tube end fittings. Learn how cut angle, orientation, and multi-side configurations affect sampling performance.
Retractable vs Fixed Sample Probes: Choosing the Right Installation Method
Compare retractable and fixed sample probe installations. Covers ball vs gate valve isolation, ejection force calculations, retaining chain requirements, installation procedures, and the center-third sampling rule.
Sample Probe Assembly Components: A Complete Guide to Every Part
Detailed breakdown of every component in a sample probe assembly stack: probe tube, PG compression gland, isolation valve, nozzle, stop collar, retaining chain, and process pipeline considerations.
Types of Sample Probe Assemblies: Fixed, Retractable, Flanged, and Threaded Configurations
Compare fixed, retractable, flanged, threaded, and socket weld sample probe assemblies. Learn when to use each configuration based on pressure, temperature, and maintenance requirements.
Conax Technologies PG Packing Glands: Complete Technical Guide
Comprehensive guide to Conax Technologies PG packing glands — PG2 through PG9 models, NPT sizes, sealant options, torque specs, and applications.
Oil and Gas Pipeline Sampling Best Practices: Ensuring Representative Samples
Best practices for pipeline sampling in oil and gas applications, covering the center-third rule, probe orientation, retaining chains, sample conditioning, dead legs, and API 14.1 compliance.
Sample Probe Material Selection Guide: Choosing the Right Alloy for Your Process Conditions
A comprehensive guide to material selection for sample probe assemblies, covering 304 SS, 316 SS, 316L NACE, Monel 400, Hastelloy C-276, and Inconel 600 with temperature limits and application guidance.
SilcoNert Coatings for Trace Gas Analysis: Ensuring Sample Integrity at the Parts-Per-Billion Level
How SilcoNert 2000 (Sulfinert) and SilcoNert 1000 chemical vapor deposition coatings improve sample probe inertness for trace sulfur, mercury, and low-level gas analysis.
Understanding Pressure Ratings and Barlow's Formula for Sample Probe Tubing
How to calculate tube pressure ratings using Barlow's formula, apply safety factors and temperature derating, and understand ASME B31.3 requirements for sample probe assemblies.
Wake Frequency Analysis and ASME PTC 19.3 TW-2016: Preventing Vortex-Induced Vibration
Understand wake frequency analysis per ASME PTC 19.3 TW-2016, Strouhal number calculations, fs/fn ratio criteria, and probe redesign strategies for thermowells and sample probes.
What Is a Sample Probe Assembly? A Comprehensive Guide for Process Engineers
Learn what a sample probe assembly is, how it works, its key components, installation process, and critical applications in pipeline instrumentation.