Onsite Post Weld Heat Treatment (PWHT) Services in Houston, TX
In industrial sectors where safety, reliability, and structural performance are non-negotiable, the integrity of a weld joint plays a critical role. For industries in Houston, TX, ranging from oil and gas refineries to petrochemical plants, power stations, and pressure vessel manufacturers, Post Weld Heat Treatment (PWHT) is not just an added precaution. It’s an essential process that ensures compliance, durability, and safety of welded components operating under extreme conditions.
At Onsite USA, we specialize in code-compliant Post Weld Heat Treatment services across Houston and Southeast Texas, delivering precision, flexibility, and results that meet or exceed industry expectations. Whether you’re managing a refinery turnaround, commissioning a new power plant, or fabricating a high-pressure vessel, our mobile and in-shop PWHT capabilities are engineered to fit the demands of your project.
What Is Onsite Post Weld Heat Treatment?
Post Weld Heat Treatment, or PWHT, is a controlled heating and cooling process applied to welded components to relieve residual stress, improve mechanical properties, and meet mandatory code requirements. Unlike traditional furnace-based PWHT, onsite heat treatment allows us to apply heat locally to the weld zone using resistance heating pads or induction coils, without removing or relocating the component.
This is especially important in industries where components are either too large, too critical, or too integrated into the process flow to be disassembled. Our field heat treatment services offer precise, efficient, and mobile solutions, suitable for live plants and active job sites throughout the Greater Houston area.
Why Is PWHT Necessary After Welding?
During the welding process, extreme localized heating and cooling introduce thermal stresses in and around the weld joint. If not properly addressed, these stresses can lead to:
- Brittle fracture or delayed cracking
- Weld failures under cyclic pressure or vibration
- Dimensional instability
- Degradation of mechanical and metallurgical properties
PWHT serves to:
- Reduce and redistribute residual stresses
- Lower hardness in the heat-affected zone (HAZ)
- Restore toughness and ductility
- Enhance corrosion resistance in alloy steels
- Achieve compliance with ASME, API, AWS, and customer-specific codes
For Houston’s industries, especially oil, gas, refining, petrochemical, and power, PWHT is often not optional. It’s a code-mandated and safety-critical requirement for many pressure-bound and high-temperature components.
Industries in Houston That Rely on Onsite PWHT Services
Houston’s industrial economy includes thousands of miles of pipelines, dozens of refineries, and complex networks of pressure vessels, tanks, structural weldments, and process piping systems. All these require periodic fabrication, repair, or upgrade, and often that involves welding.
Onsite USA supports companies in:
- Oil and gas refineries
- Petrochemical plants
- Power plants (fossil, gas, and renewables)
- Pipeline construction and maintenance
- Pressure vessel and tank repair contractors
- Offshore structures and marine fabrication
- Structural steel welding for infrastructure
We perform onsite heat treatment at facilities across Houston, including Pasadena, Baytown, Deer Park, La Porte, Sugar Land, The Woodlands, Galveston, Freeport, and surrounding areas. If your weld joint is already in place, we bring the heat to you.
Our Onsite PWHT Process Explained
Because every weld is different, our technicians begin by reviewing your project specifications, material grades, and applicable code requirements. From there, we design a custom heat treatment cycle that meets metallurgical, safety, and compliance needs.
1. Preparation and Setup
- Surface preparation for accurate thermocouple placement
- Installation of heating elements (resistance pads or coils)
- Setup of insulation and temperature control zones
2. Controlled Heating
- Gradual increase of temperature at a controlled rate (typically 100–400°F per hour depending on thickness and material)
- Continuous monitoring to avoid thermal shock or localized overheating
All heat treatment is conducted using calibrated equipment, and our certified technicians adhere strictly to customer specifications and international standards.
Equipment and Capabilities for Field PWHT
We are fully equipped to perform localized heat treatment on structural welds, piping, and pressure components, regardless of location or complexity. Our mobile systems include:
- Resistance heating consoles capable of multiple zone control
- Flexible ceramic heating blankets and metallic coils
- Digital chart recorders for real-time tracking
- K-type thermocouples and insulation materials
- Power generators and transformers (if required)
- Environmental shielding (for outdoor/remote sites)
Our equipment is deployed in refineries, plants, offshore platforms, shipyards, fabrication yards, and construction sites, delivering the same level of precision you’d expect from a fixed facility, but at your location, on your schedule.
Materials and Weld Types We Service
Our field PWHT services in Houston cover a wide range of welded materials and configurations, including:
- Carbon steel (A106, A516, A105, etc.)
- Low alloy steels (P1, P11, P22, P91, Cr-Mo alloys)
- Stainless steels, where applicable (with special procedures)
- High-strength pressure piping
- Large-diameter storage tanks
- Welded vessels, nozzles, flanges, and supports
- Weld overlays and hardfacing repairs
We also offer simulated PWHT for welding procedure qualification and can assist with preheat and post heat requirements where full PWHT is not feasible.
Codes and Standards We Comply With
As a trusted provider of onsite heat treatment services in Houston, we operate under strict code adherence, including:
- ASME Section VIII, B31.1, and B31.3
- API 650, API 1104
- AWS D1.1 for structural steel
- NACE MR0175 for sour service applications
- Customer-specific QA/QC and inspection protocols
If you’re unsure whether PWHT is required for your application, our technical team can review your specifications and determine your exact compliance needs.
Why Choose Onsite USA for Field PWHT Services in Houston?
1. We Are 100% Field-Based
Unlike other heat treatment companies that rely on in-shop furnaces, Onsite USA is built to operate entirely in the field. We bring our complete system, including power, heating, and insulation, to your site, saving you the cost, delay, and complexity of disassembly and transport.
2. Rapid Deployment Across Southeast Texas
We’re based in Houston and can quickly dispatch heat treatment crews anywhere in the metro area, including plants, ports, industrial zones, and rural job sites.
4. Documentation and Traceability
We provide complete heat treatment records, thermocouple maps, time/temperature charts, and inspection reports, required by QA departments, third-party inspectors, and regulatory audits.
Area We Serve
Our mobile PWT service is available across the entire Houston region and beyond, including:
- Houston
- Pasadena
- Baytown
- Deer Park
- La Porte
- Sugar Land
- The Woodlands
- Freeport
- Galveston
- Beaumont
- Port Arthur
Wherever your weld is, we’ll be there.
Request a Quote for Onsite PWHT Services in Houston, TX
If your project requires onsite post weld heat treatment in Houston, trust Onsite USA to deliver high-quality, code-compliant service, on your schedule, at your site, and to your exact specification.
Call us now at 346-291-2058 or fill out our request form to speak with a PWHT specialist and get a fast, customized quote.
Don’t move your welds to the heat. Let Onsite USA bring the heat to your welds.
Post Weld Heat Treatment - Houston, TX
Frequently Asked Questions
When should post-weld heat treatment be done?
PWHT should be performed after welding is complete and any required non-destructive testing (NDT) is done. It’s usually scheduled before final assembly or coating, following code requirements and material-specific temperature/time procedures.
Is post-weld heat treatment the same as stress relieving?
Not exactly. Stress relieving is one type of PWHT. While all stress relieving is PWHT, not all PWHT involves only stress relief, it may also modify microstructure, hardness, or improve ductility depending on the base metal and application.
Why do you heat treat after welding?
Heat treating after welding reduces residual stress, prevents cracking, restores material properties, and ensures weld performance under pressure or temperature. It’s often mandatory for pressure vessels, pipelines, and alloy components exposed to cyclic loads or harsh environments.
What is the most common type of post weld heat treatment?
The most common PWHT method is thermal stress relieving, where the welded component is heated to a subcritical temperature (e.g., 1100–1350°F), held for a specific time, and then cooled at a controlled rate to reduce internal stresses.
How many times can PWHT be done?
PWHT can be done multiple times if needed, but excessive cycles can degrade material properties. Each cycle must follow code limits. It’s best to consult the material’s specification or applicable code to ensure compliance and avoid embrittlement.
What is the difference between PWHT and annealing?
Annealing involves heating to a higher temperature to soften metal, improve ductility, and alter the microstructure. PWHT typically operates at lower temperatures to relieve stress without drastically changing material properties. Annealing is more transformative; PWHT is more preservative.
How to determine if PWHT is required?
PWHT requirements depend on factors like material type, thickness, service conditions, and applicable codes (ASME, API, etc.). Review the welding procedure specification (WPS) and project standards, or consult a welding engineer for accurate determination.
