Parse table with HTML Agility Pack

This method uses LINQ to query for HtmlNode instances that have the name td.

I also noticed your output appears as val|val| (with the trailing pipe), This sample uses string.Join(pipe, array) as a less-hideous method of removing that trailing pipe: val|val.

using System.Linq;

// ...

var tablecollection = doc.DocumentNode.SelectNodes("//table");
string store = string.Empty;

if (tablecollection != null)
{
    foreach (HtmlNode table in tablecollection)
    {
        // For all rows with at least one child with the 'td' tag.
        foreach (HtmlNode row in table.DescendantNodes()
            .Where(desc =>
                desc.Name.Equals("tr", StringComparison.OrdinalIgnoreCase) &&
                desc.DescendantNodes().Any(child => child.Name.Equals("td",
                    StringComparison.OrdinalIgnoreCase))))
        {
            // Combine the child 'td' elements into an array, join with the pipe
            // to create the output in 'val|val|val' format.
            store = string.Join("|", row.DescendantNodes().Where(desc =>
                desc.Name.Equals("td", StringComparison.OrdinalIgnoreCase))
                .Select(desc => desc.InnerText));

            // You can probably get rid of the 'store' variable as it's
            // no longer necessary to store the value of the table's
            // cells over the iteration.
            sw.Write(store);
            sw.WriteLine();
        }
    }
}

sw.Flush();
sw.Close();